Method for transmitting/receiving signal in wireless communication system, and device therefor

ABSTRACT

The present invention relates to a method for receiving a paging signal in a wireless communication system, and a device therefor, the method comprising the steps of: determining index information indicating a wake up signal (WUS) resource; and monitoring a WUS on the basis of the determined index information, wherein, when a user equipment (UE) supports machine type communication (MTC), the index information indicating the WUS resource is determined on the basis of identification information of the UE, parameters related to a discontinuous reception (DRX) cycle of the UE, information related to the number of paging narrowbands, and information related to the number of UE groups for the WUS.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/KR2019/010159, filed on Aug. 9, 2019, which claims the benefit ofKorean Application No. 10-2018-0114510, filed on Sep. 22, 2018, andKorean Application No. 10-2018-0093428, filed on Aug. 9, 2018. Thedisclosures of the prior applications are incorporated by reference intheir entirety.

TECHNICAL FIELD

The present disclosure relates to a wireless communication system, andmore specifically relates to a method of transmitting or receiving awake up signal (WUS) and an apparatus therefor.

BACKGROUND

Mobile communication systems were developed to provide voice serviceswhile ensuring mobility of users. However, mobile communication systemshave been extended to data services as well as voice services, and moreadvanced communication systems are needed as the explosive increase intraffic now leads to resource shortages and users demand higher speedservices.

Requirements of the next generation mobile communication systems are tosupport accommodation of explosive data traffics, dramatic increases inthroughputs per user, accommodation of significantly increased number ofconnected devices, very low end-to-end latency, and high energyefficiency. To this end, various technologies such as Dual Connectivity,Massive Multiple Input Multiple Output (Massive MIMO), In-band FullDuplex, Non-Orthogonal Multiple Access (NOMA), support of Superwideband, and Device Networking are under research.

SUMMARY

An aspect of the present disclosure is to provide a method and apparatusfor efficiently transmitting and receiving a wake-up signal (WUS).

Particularly, an aspect of the present disclosure is to provide a methodand apparatus for reducing unnecessary paging monitoring operations ofWUS-capable user equipments (UEs) by efficiently transmitting andreceiving a WUS based on UE sub-grouping for WUS transmission andreception.

It will be appreciated by persons skilled in the art that the objectsthat could be achieved with the present disclosure are not limited towhat has been particularly described hereinabove and the above and otherobjects that the present disclosure could achieve will be more clearlyunderstood from the following detailed description.

In a first aspect of the present disclosure, provided herein is a methodfor receiving a paging signal by a user equipment (UE) in a wirelesscommunication system, the method comprising: determining indexinformation indicating a wake up signal (WUS) resource; and monitoring aWUS based on the determined index information, wherein when the UEsupports machine type communication (MTC), the index informationindicating the WUS resource is determined based on identificationinformation of the UE, parameters related to a discontinuous reception(DRX) cycle of the UE, information about a number of paging narrowbands,and information about a number of UE groups for the WUS.

In a second aspect of the present disclosure, provided herein is a userequipment (UE) configured to receive a paging signal in a wirelesscommunication system, the UE comprising: a radio frequency (RF)transceiver; and a processor operatively coupled to the RF transceiver,wherein the processor is configured to determine index informationindicating a wake-up signal (WUS) resource, and monitor a WUS based onthe determined index information, and wherein when the UE supportsmachine type communication (MTC), the index information indicating theWUS resource is determined based on identification information of theUE, parameters related to a discontinuous reception (DRX) cycle of theUE, information about a number of paging narrowbands, and informationabout a number of UE groups for the WUS.

In a third aspect of the present disclosure, provided herein is anapparatus for a user equipment (UE) in a wireless communication system,the apparatus comprising: a memory including executable codes; and aprocessor operatively coupled to the memory, wherein the processor isconfigured to perform specific operations by executing the executablecodes, the specific operations comprising: determining index informationindicating a wake-up signal (WUS) resource; and monitoring a WUS basedon the determined index information, wherein when the UE supportsmachine type communication (MTC), the index information indicating theWUS resource is determined based on identification information of theUE, parameters related to a discontinuous reception (DRX) cycle of theUE, information about a number of paging narrowbands, and informationabout a number of UE groups for the WUS.

Preferably, the index information indicating the WUS resource isdetermined based on the following equation,

c _(g)=floor(UE_ID/(N*N _(S) *N _(n)))mod N _(SG)

where c_(g) represents the index information indicating the WUSresource, UE_ID represents the identification information of the UE, Nand N_(s) represent the parameters related to the DRX cycle of the UE,N_(n) represents the information about the number of paging narrowbands,and N_(SG) represents the information about the number of UE groups forthe WUS.

Preferably, the UE_ID is determined based on international mobilesubscriber identity (IMSI) information of the UE, N is determined basedon min(T, nB) and N_(S) is determined based on max(1, nB/T) where Trepresents the DRX cycle of the UE, nB is indicated through systeminformation, min(A, B) represents a smaller value among A and B, andmax(A, B) represents a larger value among A and B, and N_(n) isindicated by the system information.

Preferably, when the UE supports NarrowBand Internet of Things (NB-IoT),the index information indicating the WUS resource is determined based onthe identification information of the UE, the parameters related to theDRX cycle of the UE, a sum of weights for paging carriers, and theinformation about the number of UE groups for the WUS.

Preferably, the index information indicating the WUS resource isdetermined based on the following equation,

c _(g)=floor(UE_ID/(N*N _(S) *W))mod N _(SG)

where c_(g) represents the index information indicating the WUSresource, UE_ID represents the identification information of the UE, Nand N_(s) represent the parameters related to the DRX cycle of the UE, Wrepresents the sum of the weights for paging carriers, and N_(SG)represents the information about the number of UE groups for the WUS.

Preferably, the UE_ID is determined based on international mobilesubscriber identity (IMSI) information of the UE, N is determined basedon min(T, nB) and N_(S) is determined based on max(1, nB/T) where Trepresents the DRX cycle of the UE, nB is indicated through systeminformation, min(A, B) represents a smaller value among A and B, andmax(A, B) represents a larger value among A and B, and the weights forpaging carriers are determined based on the system information.

Preferably, the WUS resource includes a resource in at least one of atime domain, a frequency domain, or a code domain.

Preferably, the method may further includes, when detecting the WUS,receiving the paging signal in a paging occasion related to the WUS

Preferably, the index information indicating the WUS resource hops overtime.

Preferably, a hopping pattern for the index information indicating theWUS resource is determined based on a system frame number (SFN).

According to the present disclosure, a wake-up signal (WUS) may betransmitted and received efficiently.

Particularly according to the present disclosure, unnecessary pagingmonitoring operations of WUS-capable user equipments (UEs) may bereduced by efficiently transmitting and receiving a WUS based on UEsub-grouping for WUS transmission and reception.

It will be appreciated by persons skilled in the art that the effectsthat can be achieved with the present disclosure are not limited to whathas been particularly described hereinabove and other advantages of thepresent disclosure will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the disclosure, illustrate embodiments of thedisclosure and together with the description serve to explain theprinciple of the disclosure.

FIG. 1 illustrates an example of the 3GPP LTE system architecture.

FIG. 2 illustrates an example of the 3GPP NR system architecture.

FIG. 3 illustrates a radio frame structure of frame structure type 1.

FIG. 4 illustrates a radio frame structure of frame structure type 2.

FIG. 5 illustrates an example of a frame structure in NR.

FIG. 6 illustrates a resource grid for one DL slot.

FIG. 7 illustrates the structure of a downlink subframe.

FIG. 8 illustrates the structure of an uplink subframe.

FIG. 9 illustrates an example of a resource grid in NR.

FIG. 10 illustrates an example of a physical resource block in NR.

FIG. 11 illustrates a block diagram of a wireless communicationapparatus to which the methods proposed in the present disclosure areapplicable.

FIGS. 12A and 12B illustrate examples of narrowband operations andfrequency diversity.

FIG. 13 illustrates physical channels available in MTC and a generalsignal transmission method using the same.

FIGS. 14A and 14B illustrate an example of system informationtransmissions in MTC.

FIG. 15 illustrates an example of scheduling for each of MTC and legacyLTE.

FIGS. 16 and 17 illustrate examples of NB-IoT frame structures accordingto subcarrier spacing.

FIG. 18 illustrates an example of the resource grid for NB-IoT UL.

FIGS. 19A to 19C illustrate an examples of operation modes supported inthe NB-IoT system.

FIG. 20 illustrates an example of physical channels available in theNB-IoT and a general signal transmission method using the same.

FIG. 21 illustrates an example of the initial access procedure in theNB-IoT.

FIG. 22 illustrates an example of the random access procedure in theNB-IoT.

FIG. 23 illustrates an example of DRX mode in an idle state and/or aninactive state.

FIG. 24 illustrates an example of a DRX configuration and indicationprocedure for the NB-IoT UE.

FIG. 25 illustrates an exemplary timing relationship between a WUS and aPO.

FIG. 26 illustrates a flowchart of a method according to the presentdisclosure.

FIG. 27 to FIG. 32 illustrate examples of a system and an apparatus towhich the methods proposed in the present disclosure are applicable.

DETAILED DESCRIPTION

In the following, downlink (DL) refers to communication from a basestation (BS) to a user equipment (UE), and uplink (UL) refers tocommunication from the UE to the BS. In the case of DL, a transmittermay be a part of the BS, and a receiver may be a part of the UE. In thecase of UL, a transmitter may be a part of the UE, and a receiver may bea part of the BS.

The technology described herein is applicable to various wireless accesssystems such as code division multiple access (CDMA), frequency divisionmultiple access (FDMA), time division multiple access (TDMA), orthogonalfrequency division multiple access (OFDMA), single carrier frequencydivision multiple access (SC-FDMA), etc. The CDMA may be implemented asradio technology such as universal terrestrial radio access (UTRA) orCDMA2000. The TDMA may be implemented as radio technology such as globalsystem for mobile communications (GSM), general packet radio service(GPRS), or enhanced data rates for GSM evolution (EDGE). The OFDMA maybe implemented as radio technology such as the Institute of Electricaland Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX),IEEE 802-20, evolved UTRA (E-UTRA), etc. The UTRA is a part of auniversal mobile telecommunication system (UMTS). The 3rd generationpartnership project (3GPP) long term evolution (LTE) is a part of anevolved UMTS (E-UMTS) using the E-UTRA. LTE-advance (LTE-A) or LTE-A prois an evolved version of the 3GPP LTE. 3GPP new radio or new radioaccess technology (3GPP NR) is an evolved version of the 3GPP LTE,LTE-A, or LTE-A pro.

Although the present disclosure is described based on 3GPP communicationsystems (e.g., LTE-A, NR, etc.) for clarity of description, the spiritof the present disclosure is not limited thereto. The LTE refers to thetechnology beyond 3GPP technical specification (TS) 36.xxx Release 8. Inparticular, the LTE technology beyond 3GPP TS 36.xxx Release 10 isreferred to as the LTE-A, and the LTE technology beyond 3GPP TS 36.xxxRelease 13 is referred to as the LTE-A pro. The 3GPP NR refers to thetechnology beyond 3GPP TS 38.xxx Release 15. The LTE/NR may be called‘3GPP system’. Herein, “xxx” refers to a standard specification number.The LTE/NR may be commonly referred to as ‘3GPP system’. Details of thebackground, terminology, abbreviations, etc. used herein may be found indocuments published before the present disclosure. For example, thefollowing documents may be referenced.

3GPP LTE

-   -   36.211: Physical channels and modulation    -   36.212: Multiplexing and channel coding    -   36.213: Physical layer procedures    -   36.300: Overall description    -   36.304: User Equipment (UE) procedures in idle mode    -   36.331: Radio Resource Control (RRC)

3GPP NR

-   -   38.211: Physical channels and modulation    -   38.212: Multiplexing and channel coding    -   38.213: Physical layer procedures for control    -   38.214: Physical layer procedures for data    -   38.300: NR and NG-RAN Overall Description    -   38.304: User Equipment (UE) procedures in Idle mode and RRC        Inactive state    -   36.331: Radio Resource Control (RRC) protocol specification

A. System Architecture

FIG. 1 illustrates an example of the 3GPP LTE system architecture.

A wireless communication system may be referred to as an evolved-UMTSterrestrial radio access network (E-UTRAN) or a long term evolution(LTE)/LTE-A system. Referring to FIG. 1, the E-UTRAN includes at leastone BS 20 that provides control and user planes to a UE 10. The UE 10may be fixed or mobile. The UE 10 may be referred to as anotherterminology such as ‘mobile station (MS)’, ‘user terminal (UT)’,‘subscriber station (SS)’, ‘mobile terminal (MT)’, or ‘wireless device’.In general, the BS 20 may be a fixed station that communicates with theUE 10. The BS 20 may be referred to as another terminology such as‘evolved Node-B (eNB)’, ‘general Node-B (gNB)’, ‘base transceiver system(BTS)’, or ‘access point (AP)’. The BSs 20 may be interconnected throughan X2 interface. The BS 20 may be connected to an evolved packet core(EPC) through an S1 interface. More particularly, the BS 20 may beconnected to a mobility management entity (MME) through S1-MME and to aserving gateway (S-GW) through S1-U. The EPC includes the MME, the S-GW,and a packet data network-gateway (P-GW). Radio interface protocollayers between the UE and network may be classified into Layer 1 (L1),Layer 2 (L2), and Layer 3 (L3) based on three lower layers of the opensystem interconnection (OSI) model well known in communication systems.A physical (PHY) layer, which belongs to L1, provides an informationtransfer service over a physical channel. A radio resource control (RRC)layer, which belongs to L3, controls radio resources between the UE andnetwork. To this end, the BS and UE may exchange an RRC message throughthe RRC layer.

FIG. 2 illustrates an example of the 3GPP NR system architecture.

Referring to FIG. 2, a NG-RAN includes gNBs, each of which provides aNG-RA user plane (e.g., new AS sublayer/PDCP/RLC/MAC/PHY) and a controlplane (RRC) protocol terminal to a UE. The gNBs are interconnectedthrough an Xn interface. The gNB is connected to an NGC through a NGinterface. More particularly, the gNB is connected to an access andmobility management function through an N2 interface and to a user planefunction (UPF) through an N3 interface.

B. Frame Structure

Hereinafter, an LTE frame structure will be described.

In the LTE standards, the sizes of various fields in the time domain areexpressed in a time unit (Ts=1/(15000×2048) seconds) unless specifiedotherwise. DL and UL transmissions are organized in radio frames, eachof which has a duration of 10 ms (Tf=307200×Ts=10 ms). Two radio framestructures are supported.

-   -   Type 1 is applicable to frequency division duplex (FDD).    -   Type 2 is applicable to time division duplex (TDD).

(1) Frame Structure Type 1

Frame structure type 1 is applicable to both full-duplex FDD andhalf-duplex FDD. Each radio frame has a duration ofT_(f)=307200·T_(s)=10 ms and is composed of 20 slots, each of which hasa length of T_(slot)=15360·T_(s)=0.5 ms. The 20 slots are indexed from 0to 19. A subframe is composed of two consecutive slots. That is,subframe i is composed of slot 2i and slot (2i+1). In the FDD, 10subframes may be used for DL transmission, and 10 subframes may beavailable for UL transmissions at every interval of 10 ms. DL and ULtransmissions are separated in the frequency domain. However, the UE maynot perform transmission and reception simultaneously in the half-duplexFDD system.

FIG. 3 illustrates a radio frame structure of frame structure type 1.

Referring to FIG. 3, the radio frame includes 10 subframes. Eachsubframe includes two slots in the time domain. The time to transmit onesubframe is defined as a transmission time interval (TTI). For example,one subframe may have a length of 1 ms, and one slot may have a lengthof 0.5 ms. One slot may include a plurality of orthogonal frequencydivision multiplexing (OFDM) symbols in the time domain. Since the 3GPPLTE system uses OFDMA in DL, the OFDM symbol may represent one symbolperiod. The OFDM symbol may be referred to as an SC-FDMA symbol or asymbol period. A resource block (RB) is a resource allocation unit andincludes a plurality of consecutive subcarriers in one slot. This radioframe structure is merely exemplary. Therefore, the number of subframesin a radio frame, the number of slots in a subframe, or the number ofOFDM symbols in a slot may be changed in various ways.

(2) Frame Structure Type 2

Frame Structure Type 2 is Applicable to TDD. Each Radio Frame has aLength of T_(f)=307200×T_(s)=10 ms and includes two half-frames, each ofwhich has a length of 15360·T_(s)=0.5 ms. Each half-frame includes fivesubframes, each of which has a length of 30720·T_(s)=1 ms SupportedUL-DL configurations are defined in the standards. In each subframe of aradio frame, “D” denotes a subframe reserved for DL transmission, “U”denotes a subframe reserved for UL transmission, and “S” denotes aspecial subframe including the following three fields: downlink pilottime slot (DwPTS), guard period (GP), and uplink pilot time slot(UpPTS). The DwPTS may be referred to as a DL period, and the UpPTS maybe referred to as a UL period. The lengths of the DwPTS and UpPTS dependon the total length of the DwPTS, GP, and UpPTS, which is equal to30720·T_(s)=1 ms Subframe i is composed of two slots, slot 2i and slot(2i+1), each of which has a length of T_(slot)=15360·T_(s)=0.5 ms.

FIG. 4 illustrates a radio frame structure of frame structure type 2.

FIG. 4 shows that a UL-DL configuration supports DL-to-UL switch-pointperiodicities of 5 ms and 10 ms. In the case of the 5-ms DL-to-ULswitch-point periodicity, the special subframe exists across twohalf-frames. In the case of the 10-ms DL-to-UL switch-point periodicity,the special subframe exists only in the first half-frame. The DwPTS andsubframe 0 and 5 are always reserved for DL transmission, and the UpPTSand a subframe next to the special subframe are always reserved for ULtransmission.

Next, a description will be given of a frame structure of NR.

FIG. 5 illustrates an example of a frame structure in NR.

The NR system may support various numerologies. The numerology may bedefined by subcarrier spacing and cyclic prefix (CP) overhead. Multiplesubcarrier spacing may be derived by scaling basic subcarrier spacing byan integer N (or μ). In addition, even though very low subcarrierspacing is assumed not to be used at a very high subcarrier frequency, anumerology to be used may be selected independently from frequencybands. In the NR system, various frame structures may be supported basedon multiple numerologies.

Hereinafter, an OFDM numerology and a frame structure, which may beconsidered in the NR system, will be described. Table 1 shows multipleOFDM numerologies supported in the NR system.

TABLE 1 μ Δf = 2^(μ) · 15 [kHz] Cyclic prefix 0 15 Normal 1 30 Normal 260 Normal, Extended 3 120  Normal 4 240  Normal

Regarding a frame structure in the NR system, the sizes of variousfields in the time domain are expressed in multiples of a time unit,T_(s)=1/(Δf_(max)·N_(f)). In this case Δf_(max)=480·10³ and N_(f)=4096.Downlink and uplink transmissions are configured in a radio frame havinga duration of T_(f)=(Δf_(max)N_(f)/100)·T_(s)=10 ms. The radio frame iscomposed of 10 subframes, each having a duration ofT_(sf)=(Δf_(max)N_(f)/1000)·T_(s)=1 ms. In this case, there may be a setof uplink frames and a set of downlink frames. Transmission of an uplinkframe with frame number i from a UE needs to be performed earlier byT_(TA)=N_(TA)T_(s) than the start of a corresponding downlink frame ofthe UE. Regarding the numerology μ, slots are numbered in a subframe inthe following ascending order: n_(s) ^(μ)∈{0, . . . , N_(subframe)^(slots,μ)−1} and numbered in a frame in the following ascending order:n_(s,f) ^(μ)∈{0, . . . , N_(subframe) ^(slots,μ)−1}. One slot iscomposed of N_(symb) ^(μ) consecutive OFDM symbols, and N_(symb) ^(μ) isdetermined by the current numerology and slot configuration. The startsof n_(s) ^(μ) slots in a subframe are temporally aligned with those ofn_(s) ^(μ)N_(symb) ^(μ) OFDM symbols in the same subframe. Some UEs maynot perform transmission and reception at the same time, and this meansthat some OFDM symbols in a downlink slot or an uplink slot areunavailable. Table 2 shows the number of OFDM symbols per slot (N_(symb)^(slot)) the number of slots per radio frame (N_(slot) ^(frame,μ)), andthe number of slots per subframe (N_(slot) ^(subframe,μ)) in the case ofa normal CP, and Table 3 shows the number of OFDM symbols per slot, thenumber of slots per radio frame, and the number of slots per subframe inthe case of an extended CP.

TABLE 2 μ N_(symb) ^(slot) N_(slot) ^(frame,μ) N_(slot) ^(subframe,μ) 014 10 1 1 14 20 2 2 14 40 4 3 14 80 8 4 14 160  16 

TABLE 3 μ N_(symb) ^(slot) N_(slot) ^(frame,μ) N_(slot) ^(subframe,μ) 212 40 4

FIG. 5 shows an example of μ=2, i.e., 60 kHz subcarrier spacing (SCS).Referring to Table 2, one subframe may include four slots. FIG. 5 showsslots in a subframe (subframe={1, 2, 4}). In this case, the number ofslots included in the subframe may be defined as shown in Table 2 above.

In addition, a mini-slot may be composed of 2, 4, or 7 symbols.Alternatively, the number of symbols included in the mini-slot may vary.

C. Physical Resource

FIG. 6 illustrates a resource grid for one DL slot.

Referring to FIG. 6, a downlink slot includes a plurality of OFDMsymbols in the time domain. One downlink slot includes 7 OFDM symbols inthe time domain, and a resource block (RB) for example includes 12subcarriers in the frequency domain. However, the present disclosure isnot limited thereto. Each element of the resource grid is referred to asa resource element (RE). One RB includes 12×7 REs. The number of RBs inthe DL slot depends on a downlink transmission bandwidth. An uplink slotmay have the same structure as the downlink slot.

FIG. 7 illustrates the structure of a downlink subframe.

Referring to FIG. 7, up to three OFDM symbols at the start of the firstslot in a downlink subframe are used as a control region to which acontrol channel is allocated. The remaining OFDM symbols are used as adata region to which a physical downlink shared channel (PDSCH) isallocated. Downlink control channels used in the 3GPP LTE system includea physical control format indicator channel (PCFICH), a physicaldownlink control channel (PDCCH), a physical hybrid ARQ indicatorchannel (PHICH), etc. The PCFICH is transmitted in the first OFDM symbolin a subframe and carries information for the number of OFDM symbolsused for transmitting a control channel. The PHICH carries a hybridautomatic repeat request (HARD) acknowledgement/negative-acknowledgementor not-acknowledgement (ACK/NACK) signal in response to uplinktransmission. Control information transmitted on the PDCCH is referredto as downlink control information (DCI). The DCI contains uplink ordownlink scheduling information or an uplink transmission (Tx) powercontrol command for a random UE group. The PDCCH carries information forresource allocation for a downlink shared channel (DL-SCH), informationfor resource allocation for a uplink shared channel, paging informationfor a paging channel (PCH), and a DL-SCH voice over Internet protocol(VoIP) corresponding to resource allocation for a higher layer controlmessage such as a random access response transmitted on the PDSCH, a setof Tx power control commands for individual UEs in a random UE group, aTx power control command, activation of the Tx power control command,etc. Multiple PDCCHs may be transmitted in the control region, and theUE may monitor the multiple PDCCHs. The PDCCH may be transmitted on onecontrol channel element (CCE) or aggregation of multiple consecutiveCCEs. The CCE is a logical allocation unit used to provide the PDCCHwith a coding rate based on the state of a radio channel. The CCEcorresponds to a plurality of resource element groups (REGs). A PDCCHformat and the number of available PDCCH bits are determined based on arelationship between the number of CCEs and the coding rate provided bythe CCE. The base station determines the PDCCH format depending on DCIto be transmitted to the UE and adds a cyclic redundancy check (CRC) tocontrol information. The CRC is masked with a unique identifier (e.g.,radio network temporary identifier (RNTI)) according to the owner orusage of the PDCCH. If the PDCCH is for a specific UE, the CRC may bemasked with a unique UE identifier (e.g., cell-RNTI). If the PDCCH isfor a paging message, the CRC may be masked with a paging indicationidentifier (e.g., paging-RNTI (P-RNTI)). If the PDCCH is for systeminformation (more specifically, for a system information block (SIB)),the CRC may be masked with a system information identifier and a systeminformation RNTI (SI-RNTI). Further, the CRC may be masked with a randomaccess-RNTI (RA-RNTI) to indicate a random access response in responseto transmission of a random access preamble of the UE.

FIG. 8 illustrates the structure of an uplink subframe.

Referring to FIG. 8, an uplink subframe may be divided into a controlregion and a data region in the frequency domain. A physical uplinkcontrol channel (PUCCH) for carrying uplink control information may beallocated to the control region, and a physical uplink shared channel(PUSCH) for carrying user data may be allocated to the data region. TheUE may not transmit the PUCCH and the PUSCH at the same time to maintainsingle-carrier characteristics. The PUCCH for the UE is allocated to anRB pair in a subframe. The RBs included in the RB pair occupy differentsubcarriers in two slots. In other words, the RB pair allocated for thePUCCH may be frequency-hopped at a slot boundary.

As physical resources in the NR system, an antenna port, a resourcegrid, a resource element, a resource block, a carrier part, etc. may beconsidered. Hereinafter, the above physical resources considered in theNR system will be described in detail. First, an antenna port may bedefined such that a channel carrying a symbol on the antenna port isinferred from a channel carrying another symbol on the same antennaport. When the large-scale properties of a channel carrying a symbol onan antenna port are inferred from a channel carrying a symbol on anotherantenna port, the two antenna ports may be said to be in quasico-located or quasi co-location (QC/QCL) relationship. The large-scaleproperties may include at least one of delay spread, Doppler spread,frequency shift, average received power, and received timing.

FIG. 9 illustrates an example of a resource grid in NR.

Referring to the resource grid of FIG. 9, there are N_(RB) ^(μ)N_(sc)^(RB) subcarriers in the frequency domain, and there are 14·2μ OFDMsymbols in one subframe. However, the resource grid is merely exemplaryand the present disclosure is not limited thereto. In the NR system, atransmitted signal is described by one or more resource grids, eachincluding N_(RB) ^(μ)N_(sc) ^(RB) subcarriers, and 2^(μ)N_(symb) ^((μ))OFDM symbols. In this case, N_(RB) ^(μ)≤N_(RB) ^(max,μ)·N_(RB) ^(max,μ)denotes the maximum transmission bandwidth and may change not onlybetween numerologies but also between uplink and downlink. As shown inFIG. 9, one resource grid may be configured for each numerology μ andantenna port p. Each element of the resource grid for the numerology μand antenna port p is referred to as a resource element, and it isuniquely identified by an index pair (k, l), where k is an index in thefrequency domain (k=0, . . . , N_(RB) ^(μ)N_(sc) ^(RB)−1) and l denotesthe location of a symbol in the subframe (l=0, . . . , 2^(μ)N_(symb)^((μ))−1). The resource element (k,l) for the numerology μ and antennaport p corresponds to a complex value a_(k,l) ^((p,μ)). When there is norisk of confusion or when a specific antenna port or numerology is notspecified, the indexes p and μ may be dropped, and as a result, thecomplex value may be a_(k,l) ^((p)) or a_(k,l) . In addition, a resourceblock (RB) is defined as N_(sc) ^(RB)=12 consecutive subcarriers in thefrequency domain.

Point A serves as a common reference point for resource block grids andmay be obtained as follows.

-   -   OffsetToPointA for primary cell (PCell) downlink represents a        frequency offset between point A and the lowest subcarrier of        the lowest resource block in an SS/PBCH block used by the UE for        initial cell selection. OffsetToPointA is expressed in the unit        of resource block on the assumption of 15 kHz SCS for frequency        range 1 (FR1) and 60 kHz SCS for frequency range 2 (FR2).    -   AbsoluteFrequencyPointA represents the frequency location of        point A expressed as in absolute radio-frequency channel number        (ARFCN).

Common resource blocks are numbered from 0 upwards in the frequencydomain for SCS configuration μ.

The center of subcarrier 0 of common resource block 0 for the SCSconfiguration μ is equivalent to point A.

The relation between a common RB number n_(CRB) ^(μ) in the frequencydomain and a resource element (k,l) for the SCS configuration μ isdetermined as shown in Equation 1.

$\begin{matrix}{n_{CRB}^{\mu} = \left\lfloor \frac{k}{N_{sc}^{RB}} \right\rfloor} & {{Equation}\mspace{14mu} 1}\end{matrix}$

In Equation 1, k is defined relative to point A such that k=0corresponds to a subcarrier centered on point A.

Physical resource blocks are defined within a bandwidth part (BWP) andnumbered from 0 to N_(BWP,i) ^(size)−1, where i denotes the number ofthe BWP.

The relationship between a physical resource block n_(PRB) and a commonresource block n_(CRB) in BWP i is given by Equation 2.

n _(CRB) =n _(PRB) +N _(BWP,i) ^(start)  Equation 2

In Equation 2, N_(BWP,i) ^(start) is a common resource block where theBWP starts relative to common resource block 0.

FIG. 10 illustrates an example of a physical resource block in NR.

D. Wireless Communication Devices

FIG. 11 illustrates a block diagram of a wireless communicationapparatus to which the methods proposed in the present disclosure areapplicable.

Referring to FIG. 11, a wireless communication system includes a basestation 1110 and multiple UEs 1120 located within coverage of the basestation 1110. The base station 1110 and the UE may be referred to as atransmitter and a receiver, respectively, and vice versa. The basestation 1110 includes a processor 1111, a memory 1114, at least onetransmission/reception (Tx/Rx) radio frequency (RF) module (or RFtransceiver) 1115, a Tx processor 1112, an Rx processor 1113, and anantenna 1116. The UE 1120 includes a processor 1121, a memory 1124, atleast one Tx/Rx RF module (or RF transceiver) 1125, a Tx processor 1122,an Rx processor 1123, and an antenna 1126. The processors are configuredto implement the above-described functions, processes and/or methods.Specifically, the processor 1111 provides a higher layer packet from acore network for downlink (DL) transmission (communication from the basestation to the UE). The processor implements the functionality of layer2 (L2). In downlink (DL), the processor provides the UE 1120 withmultiplexing between logical and transmission channels and radioresource allocation. That is, the processor is in charge of signaling tothe UE. The Tx processor 1112 implements various signal processingfunctions of layer 1 (L1) (i.e., physical layers). The signal processingfunctions include facilitating the UE to perform forward errorcorrection (FEC) and performing coding and interleaving. Coded andmodulated symbols may be divided into parallel streams. Each stream maybe mapped to an OFDM subcarrier, multiplexed with a reference signal(RS) in the time and/or frequency domain, and then combined togetherusing an inverse fast Fourier transform (IFFT) to create a physicalchannel carrying a time domain OFDMA symbol stream. The OFDM stream isspatially precoded to produce multiple spatial streams. Each spatialstream may be provided to a different antenna 1116 through the Tx/Rxmodule (or transceiver) 1115. Each Tx/Rx module may modulate an RFcarrier with each spatial stream for transmission. At the UE, each Tx/Rxmodule (or transceiver) 1125 receives a signal through each antenna 1126thereof. Each Tx/Rx module recovers information modulated on the RFcarrier and provides the information to the RX processor 1123. The Rxprocessor implements various signal processing functions of layer 1. TheRx processor may perform spatial processing on the information torecover any spatial streams toward the UE. If multiple spatial streamsare destined for the UE, the multiple spatial streams may be combined bymultiple Rx processors into a single OFDMA symbol stream. The RXprocessor converts the OFDMA symbol stream from the time domain to thefrequency domain using a fast Fourier transform (FFT). Afrequency-domain signal includes a separate OFDMA symbol stream for eachsubcarrier of an OFDM signal. The symbols and the reference signal oneach subcarrier are recovered and demodulated by determining the mostprobable signal constellation points transmitted by the base station.Such soft decisions may be based on channel estimation values. The softdecisions are decoded and deinterleaved to recover data and controlsignals originally transmitted by the base station over the physicalchannel. The corresponding data and control signals are provided to theprocessor 1121.

Uplink (UL) transmission (communication from the UE to the base station)is processed by the base station 1110 in a similar way to that describedin regard to the receiver functions of the UE 1120. Each Tx/Rx module(or transceiver) 1125 receives a signal through each antenna 1126. EachTx/Rx module provides an RF carrier and information to the Rx processor1123. The processor 1121 may be connected to the memory 1124 storingprogram codes and data. The memory may be referred to as acomputer-readable medium.

E. Machine Type Communication (MTC)

The Machine Type Communication (MTC) refers to communication technologyadopted by 3^(rd) Generation Partnership Project (3GPP) to meet Internetof Things (IoT) service requirements. Since the MTC does not requirehigh throughput, it may be used as an application for machine-to-machine(M2M) and Internet of Things (IoT).

The MTC may be implemented to satisfy the following requirements: (i)low cost and low complexity; (ii) enhanced coverage; and (iii) low powerconsumption.

The MTC was introduced in 3GPP release 10. Hereinafter, the MTC featuresadded in each 3GPP release will be described.

The MTC load control was introduced in 3GPP releases 10 and 11.

The load control method prevents IoT (or M2M) devices from creating aheavy load on the base station suddenly.

Specifically, according to release 10, when a load occurs, the basestation may disconnect connections with IoT devices to control the load.According to release 11, the base station may prevent the UE fromattempting to establish a connection by informing the UE that accesswill become available through broadcasting such as SIB14.

In release 12, the features of low-cost MTC were added, and to this end,UE category 0 was newly defined. The UE category indicates the amount ofdata that the UE is capable of processing using a communication modem.

Specifically, a UE that belongs to UE category 0 may use a reduced peakdata rate, a half-duplex operation with relaxed RF requirements, and asingle reception antenna, thereby reducing the baseband and RFcomplexity of the UE.

In Release 13, enhanced MTC (eMTC) was introduced. In the eMTC, the UEoperates in a bandwidth of 1.08 MHz, which is the minimum frequencybandwidth supported by legacy LTE, thereby further reducing the cost andpower consumption.

Although the following description relates to the eMTC, the descriptionis equally applicable to the MTC, 5G (or NR) MTC, etc. For convenienceof description, all types of MTC is commonly referred to as ‘MTC’.

In the following description, the MTC may be referred to as anotherterminology such as ‘eMTC’, ‘LTE-M1/M2’, ‘bandwidth reduced lowcomplexity/coverage enhanced (BL/CE)’, ‘non-BL UE (in enhancedcoverage)’, ‘NR MTC’, or ‘enhanced BL/CE’. Further, the term “MTC” maybe replaced with a term defined in the future 3GPP standards.

1) General Features of MTC

(1) The MTC operates only in a specific system bandwidth (or channelbandwidth).

The specific system bandwidth may use 6 RBs of the legacy LTE as shownin Table 4 below and defined by considering the frequency range andsubcarrier spacing (SCS) shown in Tables 5 to 7. The specific systembandwidth may be referred to as narrowband (NB). Here, the legacy LTEmay encompass the contents described in the 3GPP standards expect theMTC. In the NR, the MTC may use RBs corresponding the smallest systembandwidth in Tables 6 and 7 as in the legacy LTE. Alternatively, the MTCmay operate in at least one BWP or in a specific band of a BWP.

TABLE 4 Channel bandwidth BWChannel [MHz] 1.4 3 5 10 15 20 Transmission6 15 25 50 75 100 bandwidth configuration N_(RB)

Table 5 shows the frequency ranges (FRs) defined for the NR.

TABLE 5 Frequency range designation Corresponding frequency range FR1 450 MHz-6000 MHz FR2 24250 MHz-52600 MHz

Table 6 shows the maximum transmission bandwidth configuration (NRB) forthe channel bandwidth and SCS in NR FR1.

TABLE 6 5 10 15 20 25 30 40 50 60 80 90 100 SCS MHz MHz MHz MHz MHz MHzMHz MHz MHz MHz MHz MHz (kHz) NRB NRB NRB NRB NRB NRB NRB NRB NRB NRBNRB NRB 15 25 52 79 106 133 160 216 270 N/A N/A N/A N/A 30 11 24 38 5165 78 106 133 162 217 245 273 60 N/A 11 18 24 31 38 51 65 79 107 121 135

Table 7 shows the maximum transmission bandwidth configuration (NRB) forthe channel bandwidth and SCS in NR FR2.

TABLE 7 SCS 50 MHz 100 MHz 200 MHz 400 MHz (kHz) NRB NRB NRB NRB  60 66132 264 N.A 120 32  66 132 264

Hereinafter, the MTC narrowband (NB) will be described in detail.

The MTC follows narrowband operation to transmit and receive physicalchannels and signals, and the maximum channel bandwidth is reduced to1.08 MHz or 6 (LTE) RBs.

The narrowband may be used as a reference unit for allocating resourcesto some downlink and uplink channels, and the physical location of eachnarrowband in the frequency domain may vary depending on the systembandwidth.

The 1.08 MHz bandwidth for the MTC is defined to allow an MTC UE tofollow the same cell search and random access procedures as those of thelegacy UE.

The MTC may be supported by a cell with a much larger bandwidth (e.g.,10 MHz), but the physical channels and signals transmitted/received inthe MTC are always limited to 1.08 MHz.

The larger bandwidth may be supported by the legacy LTE system, NRsystem, 5G system, etc.

The narrowband is defined as 6 non-overlapping consecutive physical RBsin the frequency domain.

If N_(NB) ^(UL)≥4, a wideband is defined as four non-overlappingnarrowbands in the frequency domain. If N_(NB) ^(UL)<4, N_(WB) ^(UL)=1and a single wideband is composed of N_(NB) ^(UL) non-overlappingnarrowband(s).

For example, in the case of a 10 MHz channel, 8 non-overlappingnarrowbands are defined.

FIGS. 12A and 12B illustrate examples of narrowband operations andfrequency diversity.

Specifically, FIG. 12A illustrates an example of the narrowbandoperation, and FIG. 12B illustrates an example of repetitions with RFretuning.

Hereinafter, frequency diversity by RF retuning will be described withreference to FIG. 12B.

The MTC supports limited frequency, spatial, and time diversity due tothe narrowband RF, single antenna, and limited mobility. To reduce theeffects of fading and outages, frequency hopping is supported betweendifferent narrowbands by the RF retuning.

The frequency hopping is applied to different uplink and downlinkphysical channels when repetition is enabled.

For example, if 32 subframes are used for PDSCH transmission, the first16 subframes may be transmitted on the first narrowband. In this case,the RF front-end is retuned to another narrowband, and the remaining 16subframes are transmitted on the second narrowband.

The MTC narrowband may be configured by system information or DCI.

(2) The MTC operates in half-duplex mode and uses limited (or reduced)maximum transmission power.

(3) The MTC does not use a channel (defined in the legacy LTE or NR)that should be distributed over the full system bandwidth of the legacyLTE or NR.

For example, the MTC does not use the following legacy LTE channels:PCFICH, PHICH, and PDCCH.

Thus, a new control channel, an MTC PDCCH (MPDCCH), is defined for theMTC since the above channels are not monitored.

The MPDCCH may occupy a maximum of 6 RBs in the frequency domain and onesubframe in the time domain.

The MPDCCH is similar to an evolved PDCCH (EPDCCH) and supports a commonsearch space for paging and random access.

In other words, the concept of the MPDCCH is similar to that of theEPDCCH used in the legacy LTE.

(4) The MTC uses newly defined DCI formats. For example, DCI formats6-0A, 6-0B, 6-1A, 6-1B, 6-2, etc. may be used.

In the MTC, a physical broadcast channel (PBCH), physical random accesschannel (PRACH), MPDCCH, PDSCH, PUCCH, and PUSCH may be repeatedlytransmitted. The MTC repeated transmission enables decoding of an MTCchannel in a poor environment such as a basement, that is, when thesignal quality or power is low, thereby increasing the radius of a cellor supporting the signal propagation effect. The MTC may support alimited number of transmission modes (TMs), which are capable ofoperating on a single layer (or single antenna), or support a channel orreference signal (RS), which are capable of operating on a single layer.For example, the MTC may operate in TM 1, 2, 6, or 9.

(6) In the MTC, HARQ retransmission is adaptive and asynchronous andperformed based on a new scheduling assignment received on the MPDCCH.

(7) In the MTC, PDSCH scheduling (DCI) and PDSCH transmission occur indifferent subframes (cross-subframe scheduling).

(8) All resource allocation information (e.g., a subframe, a transportblock size (TBS), a subband index, etc.) for SIB1 decoding is determinedby a master information block (MIB) parameter (in the MTC, no controlchannel is used for the SIB1 decoding).

(9) All resource allocation information (e.g., a subframe, a TBS, asubband index, etc.) for SIB2 decoding is determined by several SIB1parameters (in the MTC, no control channel is used for the SIB2decoding).

(10) The MTC supports an extended discontinuous reception (DRX) cycle.

(11) The MTC may use the same primary synchronization signal/secondarysynchronization signal/common reference signal (PSS/SSS/CRS) as thatused in the legacy LTE or NR. In the NR, the PSS/SSS is transmitted inthe unit of SS block (or SS/PBCH block or SSB), and a tracking RS (TRS)may be used for the same purpose as the CRS. That is, the TRS is acell-specific RS and may be used for frequency/time tracking.

2) MTC Operation Mode and Level

Hereinafter, MTC operation modes and levels will be described. Toenhance coverage, the MTC may be divided into two operation modes (firstand second modes) and four different levels as shown in Table 8 below.

The MTC operation mode may be referred to CE mode. The first and secondmodes may be referred to CE mode A and CE mode B, respectively.

TABLE 8 Mode Level Description Mode A Level 1 No repetition for PRACHLevel 2 Small Number of Repetition for PRACH Mode B Level 3 MediumNumber of Repetition for PRACH Level 4 Large Number of Repetition forPRACH

The first mode is defined for small coverage where full mobility andchannel state information (CSI) feedback are supported. In the firstmode, the number of repetitions is zero or small. The operation in thefirst mode may have the same operation coverage as that of UEcategory 1. The second mode is defined for a UE with a very poorcoverage condition where CSI feedback and limited mobility aresupported. In the second mode, the number of times that transmission isrepeated is large. The second mode provides up to 15 dB coverageenhancement with reference to the coverage of UE category 1. Each levelof the MTC is defined differently in RACH and paging procedures.

Hereinafter, a description will be given of how to determine the MTCoperation mode and level.

The MTC operation mode is determined by the base station, and each levelis determined by the MTC UE. Specifically, the base station transmitsRRC signaling including information for the MTC operation mode to theUE. The RRC signaling may include an RRC connection setup message, anRRC connection reconfiguration message, or an RRC connectionreestablishment message. Here, the term “message” may refer to aninformation element (IE).

The MTC UE determines a level within the operation mode and transmitsthe determined level to the base station. Specifically, the MTC UEdetermines the level within the operation mode based on measured channelquality (e.g., RSRP, RSRQ, SINR, etc.) and informs the base station ofthe determined level using a PRACH resource (e.g., frequency, time,preamble, etc.).

3) MTC Guard Period

As described above, the MTC operates in the narrowband. The location ofthe narrowband may vary in each specific time unit (e.g., subframe orslot). The MTC UE tunes to a different frequency in every time unit.Thus, all frequency retuning may require a certain period of time. Inother words, the guard period is required for transition from one timeunit to the next time unit, and no transmission and reception occursduring the corresponding period.

The guard period varies depending on whether the current link isdownlink or uplink and also varies depending on the state thereof. Anuplink guard period (i.e., guard period defined for uplink) variesdepending on the characteristics of data carried by a first time unit(time unit N) and a second time unit (time unit N+1). In the case of adownlink guard period, the following conditions need to be satisfied:(1) a first downlink narrowband center frequency is different from asecond narrowband center frequency; and (2) in TDD, a first uplinknarrowband center frequency is different from a second downlink centerfrequency.

The MTC guard period defined in the legacy LTE will be described. Aguard period consisting of at most N_(symb) ^(retune) SC-FDMA symbols iscreated for Tx-Tx frequency retuning between two consecutive subframes.When the higher layer parameter ce-RetuningSymbols is configured,N_(symb) ^(retune) is equal to ce-RetuningSymbols. Otherwise, N_(symb)^(retune) is 2. For an MTC UE configured with the higher layer parametersrs-UpPtsAdd, a guard period consisting of SC-FDMA symbols is createdfor Tx-Tx frequency retuning between a first special subframe and asecond uplink subframe for frame structure type 2.

FIG. 13 illustrates physical channels available in MTC and a generalsignal transmission method using the same.

When an MTC UE is powered on or enters a new cell, the MTC UE performsinitial cell search in step S1301. The initial cell search involvesacquisition of synchronization with a base station. Specifically, theMTC UE synchronizes with the base station by receiving a primarysynchronization signal (PSS) and a second synchronization signal (SSS)from the base station and obtains information such as a cell identifier(ID). The PSS/SSS used by the MTC UE for the initial cell search may beequal to a PSS/SSS or a resynchronization signal (RSS) of the legacyLTE.

Thereafter, the MTC UE may acquire broadcast information in the cell byreceiving a PBCH signal from the base station.

During the initial cell search, the MTC UE may monitor the state of adownlink channel by receiving a downlink reference signal (DL RS). Thebroadcast information transmitted on the PBCH corresponds to the MIB. Inthe MTC, the MIB is repeated in the first slot of subframe #0 of a radioframe and other subframes (subframe #9 in FDD and subframe #5 in theTDD).

The PBCH repetition is performed such that the same constellation pointis repeated on different OFDM symbols to estimate an initial frequencyerror before attempting PBCH decoding.

FIGS. 14A and 14B illustrate an example of system informationtransmissions in MTC.

Specifically, FIG. 14A illustrates an example of a repetition patternfor subframe #0 in FDD and a frequency error estimation method for anormal CP and repeated symbols, and FIG. 14B illustrates an example oftransmission of an SIB-BR on a wideband LTE channel.

Five reserved bits in the MIB are used in the MTC to transmit schedulinginformation for a new system information block for bandwidth reduceddevice (SIB1-BR) including a time/frequency location and a TBS.

The SIB-BR is transmitted on a PDSCH directly without any relatedcontrol channels.

The SIB-BR is maintained without change for 512 radio frames (5120 ms)to allow a large number of subframes to be combined.

Table 9 shows an example of the MIB.

TABLE 9 -- ASN1START MasterInformationBlock ::= SEQUENCE { dl-BandwidthENUMERATED { n6, n15, n25, n50, n75, n100}, phich-Config PHICH-Config,systemFrameNumber BIT STRING (SIZE (8)), schedulingInfoSIB1-BR-r13INTEGER (0..31), systemInfoUnchanged-BR-r15 BOOLEAN, spare BIT STRING(SIZE (4)) } -- ASN1STOP

In Table 9, the schedulingInfoSIB1-BR field indicates the index of atable that defines SystemInformationBlockType1-BR schedulinginformation. The zero value means that SystemInformationBlockType1-BR isnot scheduled. The overall function and information carried bySystemInformationBlockType1-BR (or SIB1-BR) is similar to SIB1 of thelegacy LTE. The contents of SIB1-BR may be categorized as follows: (1)PLMN; (2) cell selection criteria; and (3) scheduling information forSIB2 and other SIBs.

After completing the initial cell search, the MTC UE may acquire moredetailed system information by receiving a MPDCCH and a PDSCH based oninformation in the MPDCCH in step S1302. The MPDCCH has the followingfeatures: (1) The MPDCCH is very similar to the EPDCCH; (2) The MPDCCHmay be transmitted once or repeatedly (the number of repetitions isconfigured through higher layer signaling); (3) Multiple MPDCCHs aresupported and a set of MPDCCHs are monitored by the UE; (4) the MPDCCHis generated by combining enhanced control channel elements (eCCEs), andeach CCE includes a set of REs; and (5) the MPDCCH supports an RA-RNTI,SI-RNTI, P-RNTI, C-RNTI, temporary C-RNTI, and semi-persistentscheduling (SPS)C-RNTI.

To complete the access to the base station, the MTC UE may perform arandom access procedure in steps S1303 to S1306. The basic configurationof an RACH procedure is carried by SIB2. SIB2 includes parametersrelated to paging. A paging occasion (PO) is a subframe in which theP-RNTI is capable of being transmitted on the MPDCCH. When a P-RNTIPDCCH is repeatedly transmitted, the PO may refer to a subframe whereMPDCCH repetition is started. A paging frame (PF) is one radio frame,which may contain one or multiple POs. When DRX is used, the MTC UEmonitors one PO per DRX cycle. A paging narrowband (PNB) is onenarrowband, on which the MTC UE performs paging message reception.

To this end, the MTC UE may transmit a preamble on a PRACH (S1303) andreceive a response message (e.g., random access response (RAR)) for thepreamble on the MPDCCH and the PDSCH related thereto (S1304). In thecase of contention-based random access, the MTC UE may perform acontention resolution procedure including transmission of an additionalPRACH signal (S1305) and reception of a MPDCCH signal and a PDSCH signalrelated thereto (S1306). In the MTC, the signals and messages (e.g., Msg1, Msg 2, Msg 3, and Msg 4) transmitted during the RACH procedure may berepeatedly transmitted, and a repetition pattern may be configureddifferently depending on coverage enhancement (CE) levels. Msg 1 mayrepresent the PRACH preamble, Msg 2 may represent the RAR, Msg 3 mayrepresent uplink transmission for the RAR at the MTC UE, and Msg 4 mayrepresent downlink transmission for Msg 3 from the base station.

For random access, signaling of different PRACH resources and differentCE levels is supported. This provides the same control of the near-fareffect for the PRACH by grouping UEs that experience similar path losstogether. Up to four different PRACH resources may be signaled to theMTC UE.

The MTC UE measures RSRP using a downlink RS (e.g., CRS, CSI-RS, TRS,etc.) and selects one of random access resources based on themeasurement result. Each of four random access resources has anassociated number of PRACH repetitions and an associated number of RARrepetitions.

Thus, the MTC UE in poor coverage requires a large number of repetitionsso as to be detected by the base station successfully and needs toreceive as many RARs as the number of repetitions such that the coveragelevels thereof are satisfied.

The search spaces for RAR and contention resolution messages are definedin the system information, and the search space is independent for eachcoverage level.

A PRACH waveform used in the MTC is the same as that in the legacy LTE(for example, OFDM and Zadoff-Chu sequences).

After performing the above-described processes, the MTC UE may performreception of an MPDCCH signal and/or a PDSCH signal (S1307) andtransmission of a PUSCH signal and/or a PUCCH signal (S1308) as a normaluplink/downlink signal transmission procedure. Control information thatthe MTC UE transmits to the base station is commonly referred to asuplink control information (UCI). The UCI includes a HARQ-ACK/NACK,scheduling request, channel quality indicator (CQI), precoding matrixindicator (PMI), rank indicator (RI), etc.

When the MTC UE has established an RRC connection, the MTC UE blindlydecodes the MPDCCH in a configured search space to obtain uplink anddownlink data assignments.

In the MTC, all available OFDM symbols in a subframe are used totransmit DCI. Accordingly, time-domain multiplexing is not allowedbetween control and data channels in the subframe. Thus, thecross-subframe scheduling may be performed between the control and datachannels as described above.

If the MPDCCH is last repeated in subframe #N, the MPDCCH schedules aPDSCH assignment in subframe #N+2.

DCI carried by the MPDCCH provides information for how many times theMPDCCH is repeated so that the MTC UE may know the number of repetitionswhen PDSCH transmission is started.

The PDSCH assignment may be performed on different narrowbands. Thus,the MTC UE may need to perform retuning before decoding the PDSCHassignment.

For uplink data transmission, scheduling follows the same timing as thatof the legacy LTE. The last MPDCCH in subframe #N schedules PUSCHtransmission starting in subframe #N+4.

FIG. 15 illustrates an example of scheduling for each of MTC and legacyLTE.

A legacy LTE assignment is scheduled using the PDCCH and uses theinitial OFDM symbols in each subframe. The PDSCH is scheduled in thesame subframe in which the PDCCH is received.

On the other hand, the MTC PDSCH is cross-subframe scheduled, and onesubframe is defined between the MPDCCH and PDSCH to allow MPDCCHdecoding and RF retuning.

MTC control and data channels may be repeated for a large number ofsubframes to be decoded in an extreme coverage condition. Specifically,the MTC control and data channels may be repeated for a maximum of 256subframes for the MPDCCH and a maximum of 2048 subframes for the PDSCH

F. Narrowband-Internet of Things (NB-IoT)

The NB-IoT may refer to a system for providing low complexity and lowpower consumption based on a system bandwidth (BW) corresponding to onephysical resource block (PRB) of a wireless communication system (e.g.,LTE system, NR system, etc.).

Herein, the NB-IoT may be referred to as another terminology such as‘NB-LTE’, ‘NB-IoT enhancement’, ‘further enhanced NB-IoT’, or ‘NB-NR’.The NB-IoT may be replaced with a term defined or to be defined in the3GPP standards. For convenience of description, all types of NB-IoT iscommonly referred to as ‘NB-IoT’.

The NB-IoT may be used to implement the IoT by supporting an MTC device(or MTC UE) in a cellular system. Since one PRB of the system BW isallocated for the NB-IoT, frequency may be efficiently used. Inaddition, considering that in the NB-IoT, each UE recognizes a singlePRB as one carrier, the PRB and carrier described herein may beconsidered to have the same meaning.

Although the present disclosure describes frame structures, physicalchannels, multi-carrier operation, operation modes, and general signaltransmission and reception of the NB-IoT based on the LTE system, it isapparent that the present disclosure is applicable to thenext-generation systems (e.g., NR system, etc.). In addition, thedetails of the NB-IoT described in the present disclosure may be appliedto the MTC, which has similar purposes (e.g., low power, low cost,coverage enhancement, etc.).

1) Frame Structure and Physical Resource of NB-IoT

The NB-IoT frame structure may vary depending on subcarrier spacing.

FIGS. 16 and 17 illustrate examples of NB-IoT frame structures accordingto subcarrier spacing (SCS). Specifically, FIG. 16 illustrates a framestructure with SCS of 15 kHz, and FIG. 17 illustrates a frame structurewith SCS of 3.75 kHz. However, the NB-IoT frame structure is not limitedthereto, and different SCS (e.g., 30 kHz, etc.) may be applied to theNB-IoT by changing the time/frequency unit.

Although the present disclosure describes the NB-IoT frame structurebased on the LTE frame structure, this is merely for convenience ofdescription and the present disclosure is not limited thereto. That is,the embodiments of the present disclosure are applicable to the NB-IoTbased on the frame structure of the next-generation system (e.g., NRsystem).

Referring to FIG. 16, the NB-IoT frame structure for the 15 kHzsubcarrier spacing is the same as the frame structure of the legacysystem (LTE system). Specifically, a 10 ms NB-IoT frame may include 10NB-IoT subframes of 1 ms each, and the 1 ms NB-IoT subframe may includetwo NB-IoT slots, each having a duration of 0.5 ms. Each 0.5 ms NB-IoTslot ms may include 7 OFDM symbols.

Referring to FIG. 17, a 10 ms NB-IoT frame may include five NB-IoTsubframes of 2 ms each, and the 2 ms NB-IoT subframe may include 7 OFDMsymbols and one guard period (GP). The 2 ms NB-IoT subframe may beexpressed as an NB-IoT slot or an NB-IoT resource unit (RU).

Hereinafter, downlink and uplink physical resources for the NB-IoT willbe described.

The NB-IoT downlink physical resource may be configured based onphysical resources of other communication systems (e.g., LTE system, NRsystem, etc.) except that the system BW is composed of a specific numberof RBs (e.g., one RB=180 kHz). For example, when NB-IoT downlinksupports only the 15 kHz subcarrier spacing as described above, theNB-IoT downlink physical resource may be configured by limiting theresource grid of the LTE system illustrated in FIG. 6 to one RB (i.e.,one PRB) in the frequency domain.

The NB-IoT uplink physical resource may be configured by limiting to thesystem bandwidth to one RB as in the NB-IoT downlink. For example, whenNB-IoT uplink supports the 15 kHz and 3.75 kHz subcarrier spacing asdescribed above, a resource grid for the NB-IoT uplink may berepresented as shown in FIG. 18. The number of subcarriers N_(sc) ^(UL)and the slot period T_(slot) may be given in Table 10 below.

FIG. 18 illustrates an example of the resource grid for NB-IoT uplink.

TABLE 10 Subcarrier spacing N_(sc) ^(UL) T_(slot) Δf = 3.75 kHz 48 61440· T_(s) Δf = 15 kHz   12 15360 · T_(s)

A resource unit (RU) for the NB-IoT uplink may include SC-FDMA symbolsin the time domain and N_(symb) ^(UL)N_(slots) ^(UL) consecutivesubcarriers in the frequency domain. In frame structure type 1 (i.e.,FDD), the values of N_(sc) ^(RU) and N_(symb) ^(UL) may be given inTable 11 below. In frame structure type 2 (i.e., TDD), the values ofN_(sc) ^(RU) and N_(symb) ^(UL) may be given in Table 12.

TABLE 11 NPUSCH format Δf N_(sc) ^(RU) N_(slots) ^(UL) N_(symb) ^(UL) 13.75 kHz 1 16  7   15 kHz 1 16  3 8 6 4 12  2 2 3.75 kHz 1 4   15 kHz 14

TABLE 12 NPUSCH Supported uplink- format Δf downlink configurationsN_(sc) ^(RU) N_(slots) ^(UL) N_(symb) ^(UL) 1 3.75 kHz 1, 4 1 16  7   15kHz 1, 2, 3, 4, 5 1 16  3 8 6 4 12  2 2 3.75 kHz 1, 4 1 4   15 kHz 1, 2,3, 4, 5 1 4

2) Physical Channels of NB-IoT

A base station and/or UE that support the NB-IoT may be configured totransmit and receive physical channels and signals different from thosein the legacy system. Hereinafter, the physical channels and/or signalssupported in the NB-IoT will be described in detail.

First, the NB-IoT downlink will be described. For the NB-IoT downlink,an OFDMA scheme with the 15 kHz subcarrier spacing may be applied.Accordingly, orthogonality between subcarriers may be provided, therebysupporting coexistence with the legacy system (e.g., LTE system, NRsystem, etc.).

To distinguish the physical channels of the NB-IoT system from those ofthe legacy system, ‘N (narrowband)’ may be added. For example, DLphysical channels may be defined as follows: ‘narrowband physicalbroadcast channel (NPBCH)’, ‘narrowband physical downlink controlchannel (NPDCCH)’, ‘narrowband physical downlink shared channel(NPDSCH)’, etc. DL physical signals may be defined as follows:‘narrowband primary synchronization signal (NPSS)’, ‘narrowbandsecondary synchronization signal (NSSS)’, ‘narrowband reference signal(NRS)’, ‘narrowband positioning reference signal (NPRS)’, ‘narrowbandwake-up signal (NWUS)’, etc.

Generally, the above-described downlink physical channels and physicalsignals for the NB-IoT may be configured to be transmitted based ontime-domain multiplexing and/or frequency-domain multiplexing.

The NPBCH, NPDCCH, and NPDSCH, which are downlink channels of the NB-IoTsystem, may be repeatedly transmitted for coverage enhancement.

The NB-IoT uses newly defined DCI formats. For example, the DCI formatsfor the NB-IoT may be defined as follows: DCI format NO, DCI format N1,DCI format N2, etc.

Next, the NB-IoT uplink will be described. For the NB-IoT uplink, anSC-FDMA scheme with the subcarrier spacing of 15 kHz or 3.75 kHz may beapplied. The NB-IoT uplink may support multi-tone and single-tonetransmissions. For example, the multi-tone transmission may support the15 kHz subcarrier spacing, and the single-tone transmission may supportboth the 15 kHz and 3.75 kHz subcarrier spacing.

In the case of the NB-IoT uplink, ‘N (narrowband)’ may also be added todistinguish the physical channels of the NB-IoT system from those of thelegacy system, similarly to the NB-IoT downlink. For example, uplinkphysical channels may be defined as follows: ‘narrowband physical randomaccess channel (NPRACH)’, ‘narrowband physical uplink shared channel(NPUSCH)’, etc. UL physical signals may be defined as follows:‘narrowband demodulation reference signal (NDMRS)’.

The NPUSCH may be configured with NPUSCH format 1 and NPUSCH format 2.For example, NPUSCH format 1 is used for UL-SCH transmission (ortransfer), and NPUSCH format 2 may be used for UCI transmission such asHARQ ACK signaling.

The NPRACH, which is a downlink channel of the NB-IoT system, may berepeatedly transmitted for coverage enhancement. In this case, frequencyhopping may be applied to the repeated transmission.

3) Multi-Carrier Operation in NB-IoT

Hereinafter, the multi-carrier operation in the NB-IoT will bedescribed. The multi-carrier operation may mean that when the basestation and/or UE uses different usage of multiple carriers (i.e.,different types of multiple carriers) in transmitting and receiving achannel and/or a signal in the NB-IoT.

In general, the NB-IoT may operate in multi-carrier mode as describedabove. In this case, NB-IoT carriers may be divided into an anchor typecarrier (i.e., anchor carrier or anchor PRB) and a non-anchor typecarrier (i.e., non-anchor carrier or non-anchor PRB).

From the perspective of the base station, the anchor carrier may mean acarrier for transmitting the NPDSCH that carries the NPSS, NSSS, NPBCH,and SIB (N-SIB) for initial access. In other words, in the NB-IoT, thecarrier for initial access may be referred to as the anchor carrier, andthe remaining carrier(s) may be referred to as the non-anchor carrier.In this case, there may be one or multiple anchor carriers in thesystem.

4) Operation Mode of NB-IoT

The operation mode of the NB-IoT will be described. The NB-IoT systemmay support three operation modes. FIGS. 19A to 19C illustrate anexamples of operation modes supported in the NB-IoT system. Although thepresent disclosure describes the NB-IoT operation mode based on the LTEband, this is merely for convenience of description and the presentdisclosure is also applicable to other system bands (e.g., NR systemband).

FIG. 19A illustrates an in-band system, FIG. 19B illustrates aguard-band system, and FIG. 19C illustrates a stand-alone system. Thein-band system, guard-band system, and stand-alone system may bereferred to as in-band mode, guard-band mode, and stand-alone mode,respectively.

The in-band system may mean a system or mode that uses one specific RB(PRB) in the legacy LTE band for the NB-IoT. To operate the in-bandsystem, some RBs of the LTE system carrier may be allocated.

The guard-band system may mean a system or mode that uses a spacereserved for the guard band of the legacy LTE band for the NB-IoT. Tooperate the guard-band system, the guard band of the LTE carrier whichis not used as the RB in the LTE system may be allocated. For example,the legacy LTE band may be configured such that each LTE band has theguard band of minimum 100 kHz at the end thereof. In order to use 200kHz, two non-contiguous guard bands may be used.

The in-band system and the guard-band system may operate in a structurewhere the NB-IoT coexists in the legacy LTE band.

Meanwhile, the stand-alone system may mean a system or mode independentfrom the legacy LTE band. To operate the stand-alone system, a frequencyband (e.g., reallocated GSM carrier) used in a GSM EDGE radio accessnetwork (GERAN) may be separately allocated.

The above three operation modes may be applied independently, or two ormore operation modes may be combined and applied.

5) General Signal Transmission and Reception Procedure in NB-IoT

FIG. 20 illustrates an example of physical channels available in theNB-IoT and a general signal transmission method using the same. In awireless communication system, an NB-IoT UE may receive information froma base station in downlink (DL) and transmit information to the basestation in uplink (UL). In other words, the base station may transmitthe information to the NB-IoT UE in downlink and receive the informationfrom the NB-IoT UE in uplink in the wireless communication system.

Information transmitted and received between the base station and theNB-IoT UE may include various data and control information, and variousphysical channels may be used depending on the type/usage of informationtransmitted and received therebetween. The NB-IoT signal transmissionand reception method described with reference to FIG. 20 may beperformed by the aforementioned wireless communication apparatuses(e.g., base station and UE in FIG. 11).

When the NB-IoT UE is powered on or enters a new cell, the NB-IoT UE mayperform initial cell search (S11). The initial cell search involvesacquisition of synchronization with the base station. Specifically, theNB-IoT UE may synchronize with the base station by receiving an NPSS andan NSSS from the base station and obtain information such as a cell ID.Thereafter, the NB-IoT UE may acquire information broadcast in the cellby receiving an NPBCH from the base station. During the initial cellsearch, the NB-IoT UE may monitor the state of a downlink channel byreceiving a downlink reference signal (DL RS).

In other words, when the NB-IoT UE enters the new cell, the BS mayperform the initial cell search, and more particularly, the base stationmay synchronize with the UE. Specifically, the base station maysynchronize with the NB-IoT UE by transmitting the NPSS and NSSS to theUE and transmit the information such as the cell ID. The base stationmay transmit the broadcast information in the cell by transmitting (orbroadcasting) the NPBCH to the NB-IoT UE. The BS may transmit the DL RSto the NB-IoT UE during the initial cell search to check the downlinkchannel state.

After completing the initial cell search, the NB-IoT UE may acquire moredetailed system information by receiving a NPDCCH and a NPDSCH relatedto thereto (S12). In other words, after the initial cell search, thebase station may transmit the more detailed system information bytransmitting the NPDCCH and the NPDSCH related to thereto to the NB-IoTUE.

Thereafter, the NB-IoT UE may perform a random access procedure tocomplete the access to the base station (S13 to S16).

Specifically, the NB-IoT UE may transmit a preamble on an NPRACH (S13).As described above, the NPRACH may be repeatedly transmitted based onfrequency hopping for coverage enhancement. In other words, the basestation may (repeatedly) receive the preamble from the NB-IoT UE overthe NPRACH.

Then, the NB-IoT UE may receive a random access response (RAR) for thepreamble from the base station on the NPDCCH and the NPDSCH relatedthereto (S14). That is, the base station may transmit the random accessresponse (RAR) for the preamble to the base station on the NPDCCH andthe NPDSCH related thereto.

The NB-IoT UE may transmit an NPUSCH using scheduling information in theRAR (S15) and perform a contention resolution procedure based on theNPDCCH and the NPDSCH related thereto (S16). That is, the base stationmay receive the NPUSCH from the NB-IoT UE based on the schedulinginformation in the RAR and perform the contention resolution procedure.

After performing the above-described processes, the NB-IoT UE mayperform NPDCCH/NPDSCH reception (S17) and NPUSCH transmission (S18) as anormal UL/DL signal transmission procedure. After the above-describedprocesses, the base station may transmit the NPDCCH/NPDSCH to the NB-IoTUE and receive the NPUSCH from the NB-IoT UE during the normaluplink/downlink signal transmission procedure.

In the NB-IoT, the NPBCH, NPDCCH, NPDSCH, etc. may be repeatedlytransmitted for the coverage enhancement as described above. Inaddition, UL-SCH (normal uplink data) and UCI may be transmitted on theNPUSCH. In this case, the UL-SCH and UCI may be configured to betransmitted in different NPUSCH formats (e.g., NPUSCH format 1, NPUSCHformat 2, etc.)

As described above, the UCI means control information transmitted fromthe UE to the base station. The UCI may include the HARQ ACK/NACK,scheduling request (SR), CSI, etc. The CSI may include the CQI, PMI, RI,etc. Generally, the UCI may be transmitted over the NPUSCH in the NB-IoTas described above. In particular, the UE may transmit the UCI on theNPUSCH periodically, aperiodically, or semi-persistently according tothe request/indication from the network (e.g., base station).

6) Initial Access Procedure in NB-IoT

The procedure in which the NB-IoT UE initially accesses the BS isbriefly described in the section “General Signal Transmission andReception Procedure in NB-IoT”. Specifically, the above procedure may besubdivided into a procedure in which the NB-IoT UE searches for aninitial cell and a procedure in which the NB-IoT UE obtains systeminformation.

FIG. 21 illustrates a particular procedure for signaling between a UEand a BS (e.g., NodeB, eNodeB, eNB, gNB, etc.) for initial access in theNB-IoT. In the following, a normal initial access procedure, anNPSS/NSSS configuration, and acquisition of system information (e.g.,MIB, SIB, etc.) in the NB-IoT will be described with reference to FIG.21.

FIG. 21 illustrates an example of the initial access procedure in theNB-IoT. The name of each physical channel and/or signal may varydepending on the wireless communication system to which the NB-IoT isapplied. For example, although the NB-IoT based on the LTE system isconsidered in FIG. 21, this is merely for convenience of description anddetails thereof are applicable to the NB-IoT based on the NR system. Thedetails of the initial access procedure are also applicable to the MTC.

Referring to FIG. 21, the NB-IoT UE may receive a narrowbandsynchronization signal (e.g., NPSS, NSSS, etc.) from the base station(S2110 and S2120). The narrowband synchronization signal may betransmitted through physical layer signaling.

The NB-IoT UE may receive a master information block (MIB) (e.g.,MIB-NB) from the base station on an NPBCH (S2130). The MIB may betransmitted through higher layer signaling (e.g., RRC signaling).

The NB-IoT UE may receive a system information block (SIB) from the basestation on an NPDSH (S2140 and S2150). Specifically, the NB-IoT UE mayreceive SIB1-NB, SIB2-NB, etc. on the NPDSCH through the higher layersignaling (e.g., RRC signaling). For example, SIB1-NB may refer tosystem information with high priority among SIBs, and SIB2-NB may referto system information with lower priority than SIB1-NB.

The NB-IoT may receive an NRS from the BS (S2160), and this operationmay be performed through physical layer signaling.

7) Random Access Procedure in NB-IoT

The procedure in which the NB-IoT UE performs random access to the basestation is briefly described in the section “General Signal Transmissionand Reception Procedure in NB-IoT”. Specifically, the above proceduremay be subdivided into a procedure in which the NB-IoT UE transmits apreamble to the base station and a procedure in which the NB-IoTreceives a response for the preamble.

FIG. 22 illustrates a particular procedure for signaling between a UEand a base station (e.g., NodeB, eNodeB, eNB, gNB, etc.) for randomaccess in the NB-IoT. In the following, detail of the random accessprocedure in the NB-IoT will be described based on messages (e.g., msg1,msg2, msg3, msg4) used therefor.

FIG. 22 illustrates an example of the random access procedure in theNB-IoT. The name of each physical channel, physical signal, and/ormessage may vary depending on the wireless communication system to whichthe NB-IoT is applied. For example, although the NB-IoT based on the LTEsystem is considered in FIG. 22, this is merely for convenience ofdescription and details thereof are applicable to the NB-IoT based onthe NR system. The details of the initial access procedure are alsoapplicable to the MTC.

Referring to FIG. 22, the NB-IoT may be configured to supportcontention-based random access.

First, the NB-IoT UE may select an NPRACH resource based on the coveragelevel of the corresponding UE. The NB-IoT UE may transmit a randomaccess preamble (i.e., message 1, msg1) to the base station on theselected NPRACH resource.

The NB-IoT UE may monitor an NPDCCH search space to search for an NPDCCHfor DCI scrambled with an RA-RNTI (e.g., DCI format N1). Upon receivingthe NPDCCH for the DCI scrambled with the RA-RNTI, the UE may receive anRAR (i.e., message 2, msg2) from the base station on an NPDSCH relatedto the NPDCCH. The NB-IoT UE may obtain a temporary identifier (e.g.,temporary C-RNTI), a timing advance (TA) command, etc. from the RAR. Inaddition, the RAR may also provide an uplink grant for a scheduledmessage (i.e., message 3, msg3).

To start a contention resolution procedure, the NB-IoT UE may transmitthe scheduled message to the base station. Then, the base station maytransmit an associated contention resolution message (i.e., message 4,msg4) to the NB-IoT UE in order to inform that the random accessprocedure is successfully completed.

By doing the above, the base station and the NB-IoT UE may complete therandom access.

8) DRX Procedure in NB-IoT

While performing the general signal transmission and reception procedureof the NB-IoT, the NB-IoT UE may transit to an idle state (e.g., RRCIDLE state) and/or an inactive state (e.g., RRC_INACTIVE state) toreduce power consumption. The NB-IoT UE may be configured to operate inDRX mode after transiting to the idle state and/or the inactive state.For example, after transiting to the idle state and/or the inactivestate, the NB-IoT UE may be configured to monitor an NPDCCH related topaging only in a specific subframe (frame or slot) according to a DRXcycle determined by the BS. Here, the NPDCCH related to paging may referto an NPDCCH scrambled with a P-RNTI.

FIG. 23 illustrates an example of DRX mode in an idle state and/or aninactive state.

A DRX configuration and indication for the NB-IoT UE may be provided asshown in FIG. 24. That is, FIG. 24 illustrates an example of a DRXconfiguration and indication procedure for the NB-IoT UE. However, theprocedure in FIG. 24 is merely exemplary, and the methods proposed inthe present disclosure are not limited thereto.

Referring to FIG. 24, the NB-IoT UE may receive DRX configurationinformation from the base station (e.g., NodeB, eNodeB, eNB, gNB, etc.)(S2410). In this case, the UE may receive the information from the basestation through higher layer signaling (e.g., RRC signaling). The DRXconfiguration information may include DRX cycle information, a DRXoffset, configuration information for DRX-related timers, etc.

Thereafter, the NB-IoT UE may receive a DRX command from the basestation (S2420). In this case, the UE may receive the DRX command fromthe base station through higher layer signaling (e.g., MAC-CEsignaling).

Upon receiving the DRX command, the NB-IoT UE may monitor an NPDCCH in aspecific time unit (e.g., subframe, slot, etc.) based on the DRX cycle(S2430). The NPDCCH monitoring may mean a process of decoding a specificportion of the NPDCCH based on a DCI format to be received in acorresponding search space and scrambling a corresponding CRC with aspecific predefined RNTI value in order to check whether the scrambledCRC matches (i.e. corresponds to) a desired value.

When the NB-IoT UE receives its paging ID and/or information indicatingthat system information is changed over the NPDCCH during the processshown in FIG. 24, the NB-IoT UE may initialize (or reconfigure) theconnection (e.g., RRC connection) with the base station (for example,the UE may perform the cell search procedure of FIG. 20). Alternatively,the NB-IoT UE may receive (or obtain) new system information from thebase station (for example, the UE may perform the system informationacquisition procedure of FIG. 20).

G. Proposal for Sub-Grouping WUS-Capable UEs

In an LTE system, a user equipment (UE) may determine a position atwhich the UE will monitor paging based on a paging occasion (PO) andpaging frame (PF) determined based on its UE_ID. The same technical ideais applied to NB-IoT and MTC which have been newly introduced to the3GPP LTE Rel-13 standard. A plurality of UEs may expect paging in onePO, and the number of the UEs may be determined according to aconfiguration in an SIB transmitted by a base station (B S).Hereinafter, a group of a plurality of UEs which may expect paging inthe same PO will be defined as a UE-group-per-PO.

A method of using a wake-up signal (WUS) for power saving of a UE hasbeen introduced to the Rel-15 NB-IoT and MTC standard. In this method, aUE capable of using the WUS, that is, a WUS-capable UE attempts todetect the WUS based on information configured by a BS before monitoringa search space for paging. When the UE detects the WUS, the UE mayexpect transmission of paging in POs related to the position ofdetecting the WUS and monitor the search space for paging. When the UEfails to detect the WUS, the UE may not monitor (or skip monitoring) thesearch space for paging. The Rel-15 standard defines that a WUStransmission position is determined to be a position relative to a POindicated by the WUS, and all WUS-capable UEs monitoring the same POshare the same WUS and the same WUS transmission position. Accordingly,when a WUS transmitted for a specific PO is present, all WUS-capable UEsin a UE-group-per-PO corresponding to the PO should perform pagingmonitoring.

FIG. 25 illustrates an exemplary timing relationship between a WUS and aPO.

A UE may receive WUS configuration information from a BS and monitor aWUS based on the WUS configuration information. More specifically, theUE receives the configuration information related to the WUS from the BSby higher-layer signaling. The UE monitors/receives the WUS from the BSduring a configured maximum WUS duration.

The WUS configuration information may include, for example, informationabout the maximum WUS duration, the number of consecutive POs related tothe WUS, and a gap. The maximum WUS duration is a maximum time periodduring which the WUS is transmittable, which may be expressed as a ratioof a maximum repetition number (e.g., Rmax) related to a PDCCH. The WUSmay be transmitted repeatedly one or more times during the maximum WUSduration. The number of POs related to the WUS is the number of POs inwhich the UE will not monitor a channel related to paging, when the UEfails to detect the WUS (or the number of POs in which the UE willmonitor the channel related to paging, when the UE detects the WUS). Thegap information indicates a time gap between the end of the maximum WUSduration and the first PO related to the WUS.

A WUS duration may be short for a UE in good coverage and long for a UEin bad coverage. Upon detection of the WUS, a UE does not monitor theWUS until the first PO related to the WUS. The UE does not monitor theWUS either during a gap duration. Therefore, when the UE fails to detectthe WUS during the maximum WUS duration, the UE does not monitor thechannel related to paging in the POs related to the WUS (or the UEremains in sleep mode).

Paging may be transmitted only to a part of the UEs of the sameUE-group-per-PO according to determination of a mobility managemententity (MME) or a BS (eNB or gNB). Because according to the currentstandard, information indicating UEs to which a WUS and paging aredirected among the UEs of a UE-group-per-PO is delivered on an NPDSCHcarrying paging traffic, some UEs may perform unnecessary NPDCCH/NPDSCHdecoding.

Particularly, for an NB-IoT UE and an MTC UE, a PDCCH (MPDCCH or NPDCCH)and PDSCH (or NPDSCH) for paging reception may be repeatedly transmittedand received tens of times to a few thousand times, for coverageenhancement. When paging is directed only to a part of the UEs of aUE-group-per-PO, UEs to which the paging is not directed may identifythe absence of paging for the UEs only after decoding both of a PDCCH(MPDCCH or NPDCCH) and a related PDSCH (or NPDSCH) as well as afterdetecting the WUS. Accordingly, the UEs may suffer from much unnecessarypower consumption due to the unnecessary operation of receiving the WUS,the PDCCH (MPDCCH or NPDCCH), and the related PDSCH (or NPDSCH).

In light of the above problem, the present disclosure proposes criteriafor applying a WUS based on UE sub-grouping and methods of configuringthe UE sub-grouping, in order to reduce unnecessary paging monitoring ofWUS-capable UEs. Each UE sub-group configured in the proposed methods ofthe present disclosure may be configured independently with a WUSdistinguished by a time-domain resource, frequency-domain resource,and/or code-domain resource. In the following description, a specifictime-domain resource, frequency-domain resource, and/or code-domainresource configurable for a specific UE sub-group to transmit andreceive a WUS is referred to as a WUS resource.

While the proposed methods of the present disclosure are described belowin the context of NB-IoT and MTC, it is apparent that the same technicalidea is generally applicable to any communication system. Further, whilethe proposed methods of the present disclosure are described in thecontext of a WUS indicating whether paging will be transmitted in IDLEmode, it is apparent that the same technical idea is generallyapplicable to any signal (or channel) used to indicate additionalinformation about a channel (or signal) serving any purpose (e.g.,information indicating whether the channel (or signal) is to betransmitted).

Further, while the present disclosure is described based on an LTEstandard (e.g., 3GPP technical specification 36 series), the presentdisclosure may be applied in the same/similar manner to a 5G/NR system.In this case, in relation to a frame structure, the term “subframe” maybe replaced with “slot” (e.g., refer to FIGS. 5 and 9 and a relateddescription) in the 5G/NR system.

Although the proposed methods of the present disclosure may be performedindependently of each other, it is apparent that they may be performedin combination, unless conflicting with each other.

In the present disclosure, a WUS refers to a signal used to indicatewhether a UE should monitor a PDCCH (MPDCCH or NPDCCH) to receive paging(in a specific cell). The WUS is associated with one or more POsaccording to whether extended discontinuous reception (DRX) isconfigured.

A UE (which has received the WUS) may additionally perform theafore-described DRX operation and/or cell reselection operation.

A more specific UE operation and BS operation related to reception of aWUS (e.g., MTC wake-up signal (MWUS) or narrowband wake-up signal (NWUS)may be summarized as follows and may apparently be described in relationto methods described later.

(1) Base Station (BS) Operation

A BS first generates a sequence (used) for a WUS in a specific subframe.For example, the BS may generate the sequence (used) for the WUS byusing an equation defined in 3GPP technical specification (TS) 36.211V15.2.0. More specifically, the sequence w(m) (used) for the WUS may begenerated based on Equation 3.

$\begin{matrix}{\mspace{79mu} {{{w(m)} = {{\theta_{n_{f},n_{s}}\left( m^{\prime} \right)} \cdot e^{- \frac{j\; \pi \; {{un}{({n + 1})}}}{131}}}}\mspace{20mu} {{m = 0},1,\ldots \mspace{14mu},131}\mspace{20mu} {m^{\prime} = {{m + {132x\mspace{20mu} n}} = {{m\; {{mod}132}{\theta_{{nf},n_{s}}\left( m^{\prime} \right)}} = \left\{ {{\begin{matrix}{1,} & {{{if}\mspace{14mu} {c_{n_{f},n_{s}}\left( {2m^{\prime}} \right)}} = {{0\mspace{14mu} {and}\mspace{14mu} {c_{n_{f},n_{s}}\left( {{2m^{\prime}} + 1} \right)}} = 0}} \\{{- 1},} & {{{if}\mspace{14mu} {c_{n_{f},n_{s}}\left( {2m^{\prime}} \right)}} = {{0\mspace{14mu} {and}\mspace{14mu} {c_{n_{f},n_{s}}\left( {{2m^{\prime}} + 1} \right)}} = 1}} \\{j,} & {{{if}\mspace{14mu} {c_{n_{f},n_{s}}\left( {2m^{\prime}} \right)}} = {{1\mspace{14mu} {and}\mspace{14mu} {c_{n_{f},n_{s}}\left( {{2m^{\prime}} + 1} \right)}} = 0}} \\{{- j},} & {{{if}\mspace{14mu} {c_{n_{f},n_{s}}\left( {2m^{\prime}} \right)}} = {{1\mspace{14mu} {and}\mspace{14mu} {c_{n_{f},n_{s}}\left( {{2m^{\prime}} + 1} \right)}} = 1}}\end{matrix}\mspace{20mu} u} = {\left( {N_{ID}^{Ncell}{mod}\ 126} \right) + 3}} \right.}}}}} & {{Equation}\mspace{14mu} 3}\end{matrix}$

In Equation 3, x represents a subframe carrying the WUS, ranging from 0to M−1 where M is the number of subframes carrying the WUS,corresponding to an actual WUS duration. Further, in Equation 3,

$e^{- \frac{j\; \pi \; {{un}{({n + 1})}}}{131}}$

represents a Zadoff-Chu (ZC) sequence and θ_(n) _(f) _(,n) _(s) (m′)represents a complex-valued symbol related to a scrambling sequence.N_(ID) ^(Ncell) represents a physical layer cell identity (ID), andc_(n) _(f) _(,n) _(s) (i) represents a scrambling sequence which mayhave a sample length of 2*132M. Herein, i may range from 0 to 2*132M−1.The scrambling sequence may be given based on a Gold sequence.

The BS maps the generated sequence to at least one resource element(RE), and transmits the WUS on the mapped RE(s) to a UE.

In concept, the at least one RE may cover at least one of a timeresource, a frequency resource, or an antenna port.

(2) User Equipment (UE) Operation

The UE receives the WUS from the BS (or the UE may assume that the WUSis transmitted on specific RE(s) from the BS) (e.g., refer to step S2604in FIG. 26).

The UE may then identify (or determine) whether paging will be received,based on the received WUS (e.g., refer to step S2606 in FIG. 26).

When paging is transmitted, the UE receives the paging based on theafore-described paging reception-related operation, and performs an RRCidle mode-to-RRC connected mode transmission procedure.

G.1 UE Sub-Grouping Criteria

The present disclosure proposes a method of determining a condition forapplying UE sub-grouping and configuring the UE sub-grouping by a basestation and a method of recognizing and performing the UE sub-groupingby a UE, when the UE sub-grouping is applied to WUS transmission andreception. One or a combination of two or more of the following Method1-1, Method 1-2, Method 1-3, Method 1-4, Method 1-5, Method 1-6, orMethod 1-7 can be used as a method of performing the UE sub-grouping.

[Method 1-1] Method of Performing UE Sub-Grouping for a WUS Based onUE_ID

In Method 1-1, it is proposed that UE sub-grouping is performed for aWUS based on the UE_IDs of UEs. UE_ID is UE identification informationbased on an international mobile subscriber identity (IMSI).Characteristically, the definition of UE_ID used to determine a PO in3GPP TS 36.304 V15.0.0. may be used for UE_ID herein. For example, whena P-RNTI is monitored on a PDCCH, UE_ID may be given as (IMSI mod 1024).When a P-RNTI is monitored on an NPDCCH, UE_ID may be given as (IMSI mod4096). When a P-RNTI is monitored on an MPDCCH, UE_ID may be given as(IMSI mod 16394). Herein, mod represents a modulo operation.

A PF, a PO, and a paging narrowband (PNB) are determined based on DRXparameters provided in system information according to Equation 4,Equation 5, and Equation 6.

Specifically, the PF is determined by Equation 4.

SFN mod T=(T div N)*(UE_ID mod N)  Equation 4

An index i_s indicating a PO from a paging-related subframe pattern isderived by Equation 5.

i_s=floor(UE_ID/N)mod N _(s)  [Equation 5]

When the P-RNTI is monitored on the MPDCCH (or NPDCCH), the PNB isdetermined by Equation 6.

PNB=floor(UE_ID/(N*N _(s)))mod N _(n)  Equation 6

The parameters used in Equation 4, Equation 5, and Equation 6 aredefined as follows, mod represents a modulo operation, floor representsa floor function, / represents division, * represents multiplication,div represents a function of obtaining a quotient, min(A, B) representsthe smaller value among A and B, and max (A, B) represents the largervalue among A and B.

T: DRX cycle of the UE

nB: 4T, 2T, T, T/2, T/4, T/8, T/16, T/32, T/64, T/128, and T/256, andfor NB-IoT also T/512, and T/1024

N: min(T,nB)

N_(s): max(1,nB/T)

N_(n): number of paging narrowbands (for P-RNTI monitored on MPDCCH) orpaging carriers (for P-RNTI monitored on NPDCCH) provided in systeminformation

Uniform Sub-Grouping Method

As a characteristic example of Method 1-1, a method of uniformlydistributing UE_IDs to UE sub-groups may be considered. In MTC, when theindex of each UE sub-group is defined as c_(g) based on UE_IDs, c_(g)may be determined by Equation (Eq-1-1-a-MTC). In NB-IoT, when the indexof each UE sub-group is defined as c_(g) based on UE_IDs, c_(g) may bedetermined by Equation (Eq-1-1-a-NB). In Equation (Eq-1-1-a-MTC) andEquation (Eq-1-1-a-NB), UE_ID, N_(S), N_(n), and W conform to thedefinitions of Section 7 of 3GPP TS 36.304 V15.0.0 (e.g., refer to thedescription related to Equation 4, Equation 5, and Equation 6). N_(SG)represents the number of deployed sub-groups. The UE may select a WUSresource (e.g., a time-domain resource, frequency-domain resource,and/or code-domain resource) corresponding to a UE sub-group indexcalculated by Equation (Eq-1-1-a-MTC) or Equation (Eq-1-1-a-NB) andmonitor a WUS in the selected WUS resource.

c _(g)=floor(UE_ID/(N*N _(S) *N _(n)))mod N _(SG)  (Eq-1-1-a-MTC)

c _(g)=floor(UE_ID/(N*N _(S) *W))mod N _(SG)  (Eq-1-1-a-NB)

When sub-group index 0 (c_(g)=0) is used as an index for representing acommon WUS (e.g., a WUS that all WUS-capable UEs may identifyirrespective of UE sub-groups), Equation (Eq-1-1-a-MTC2) or Equation(Eq-1-1-a-NB2) may be used to prevent a specific UE sub-group fromselecting subgroup index 0 (c_(g)=0).

c _(g)=floor(UE_ID/(N*N _(S) *N _(n)))mod N _(SG)+1  (Eq-1-1-a-MTC2)

c _(g)=floor(UE_ID/(N*N _(S) *W))mod N _(SG)+1  (Eq-1-1-a-NB2)

Non-Uniform Sub-Grouping Method

As another characteristic example of Method 1-1, a method ofnon-uniformly distributing UE_IDs to UE sub-groups may be considered.This may be intended to reduce the selection frequency of a WUS resourcecorresponding to a specific UE sub-group. For example, when a WUScorresponding to a specific UE sub-group shares the same resource with alegacy WUS (e.g., a WUS for a UE to which UE sub-grouping is notapplied), the above operation may be intended to control effects onlegacy WUS-capable UEs. In MTC, when the index of each UE sub-group isdefined as c_(g) based on UE_IDs, c_(g) may be determined to be asmallest index c_(g) (0≤c_(g)≤N_(SG)−1) satisfying Equation(Eq-1-1-b-MTC). In NB-IoT, c_(g) may be determined to be a smallestindex c_(g) (0≤c_(g)≤N_(SG)−1) satisfying Equation (Eq-1-1-b-NB). N_(SG)represents the number of used sub-groups. In Equation (Eq-1-1-b-MTC) andEquation (Eq-1-1-b-NB), UE_ID, N_(S), N_(n), and W are defined inSection 7 of 3GPP TS 36.304 V15.0.0 (e.g., refer to the descriptions ofEquation 4, Equation 5, and Equation 6). In the following mathematicalformula, W_(WUS)(n) represents a weight for an n^(th) UE sub-group, fornon-uniformly distributing UE_IDs to UE sub-groups so that each UEsub-group includes a different number of UE_IDs, and W_(WUS) representsthe sum of the weights of all sub-groups. Accordingly,

W _(WUS) =W _(WUS)(0)+W _(WUS)(1)+ . . . +W _(WUS)(N _(SG)−1).

floor(UE_ID/(N*N _(S) *N _(n)))mod W _(WUS) <W _(WUS)(0)+W _(WUS)(1)+ .. . +W _(WUS)(c _(g))  (Eq-1-1-b-MTC)

floor(UE_ID/(N*N _(S) *W))mod W _(WUS) <W _(WUS)(0)+W _(WUS)(1)+ . . .+W _(WUS)(c _(g))  (Eq-1-1-b-NB)

W_(WUS)(n) corresponding to a specific index may be determined to be aweight for a sub-group sharing the same resource with a legacy WUS(e.g., W_(WUS)(0)).

When sub-group index 0 (c_(g)=0) is used as an index indicating a commonWUS (e.g., a WUS that all WUS-capable UEs may identify irrespective ofUE sub-groups), Equation (Eq-1-1-b-MTC2) or Equation (Eq-1-1-b-NB2) maybe used to prevent a specific UE sub-group from selecting subgroup index0 (c_(g)=0).

floor(UE_ID/(N*N _(S) *N _(n)))mod W _(WUS) <W _(WUS)(1)+W _(WUS)(2)+ .. . +W _(WUS)(c _(g))  (Eq-1-1-b-MTC2)

floor(UE_ID/(N*N _(S) *W))mod W _(WUS) <W _(WUS)(1)+W _(WUS)(2)+ . . .+W _(WUS)(c _(g))  (Eq-1-1-b-NB2)

In the above mathematical formula, c_(g) may be determined to satisfythe condition that 1≤c_(g)≤N_(SG).

The values of W_(WUS)(n) may be signaled by a system information block(SIB) or higher-layer signaling such as radio resource control (RRC)signaling. This signaling may be intended to adjust distribution ofUE_IDs per sub-group according to a situation. For example, the basestation (BS) may configure N_(SG) weights for the respective sub-groupsby an SIB. This operation may advantageously lead to flexible control ofUE_ID distribution ratios across all sub-groups. In another example, theBS may configure a weight (e.g., W_(WUS)(0)) for a sub-group sharing thesame resource with a legacy WUS and a weight (e.g., W_(WUS)(n), for alln not zero) for a sub-group using a different resource from the legacyWUS by an SIB. This operation may be intended to uniformly distributeUE_IDs among sub-groups using resources distinguished from resources forthe legacy WUS, while variably controlling effects on the legacy WUS. Inanother example, the BS may configure a ratio between a weight for asub-group sharing the same resource with the legacy WUS and a weight fora sub-group using a different resource from the legacy WUS by an SIB.This operation may advantageously reduce signaling overhead under thepremise that the resources used for the legacy WUS are always used for aspecific sub-group. Instead of the ratio between the two weights, theweight for the sub-group sharing the same resource with the legacy WUSmay always be fixed to 1, while only the weight for the sub-group usinga different resource from the legacy WUS may be configured.

In another method of non-uniformly distributing UE_IDs to UE sub-groups,the indexes of the UE sub-groups may be determined by a method ofuniformly distributing UE_IDs (e.g., Eq-1-1-a-MTC or Eq-1-1-a-NB), and aWUS resource corresponding to each sub-group index may be determined byan SIB or higher-layer signaling such as RRC signaling. Herein, whenUE_IDs are non-uniformly distributed such that a plurality of sub-groupindexes correspond to a specific WUS resource, the effect that thenumber of UE_IDs is non-uniform for each WUS resource may be expected.

[Method 1-2] Method of Performing UE Sub-Grouping for a WUS Based onCoverage Levels.

In Method 1-2, it is proposed that UE sub-grouping is performed for aWUS based on the coverage levels of UEs. The coverage level of a UErefers to the state of a wireless channel environment in which the UE isplaced. In a characteristic example, a coverage level may be representedby, for example, a measurement such as reference signal received power(RSRP)/reference signal received quality (RSRQ) measured by the UE or arepetition number that the UE uses to transmit and receive an uplink(UL) or downlink (DL) channel.

An RSRP/RSRQ value may be represented as quality information related achannel quality.

In Method 1-2, when a UE identifies a change in its coverage level, theUE may indicate the change to a BS. In a characteristic example, when anRSRP/RSRQ value measured by the UE changes and thus does not satisfy thecoverage level requirement of a current UE sub-group, the UE mayindicate the change of the coverage level to the BS in a random accessprocedure. In a more specific example, the UE may use an idle-mode ULdata transmission scheme such as early data transmission (EDT) to avoidunnecessary transition to the RRC connected mode. To ensure stablereporting of the coverage level of the UE, the BS may configure anadditional RACH resource for coverage level reporting and indicate theconfiguration to the UE.

[Method 1-3] Method of Performing UE Sub-Grouping for a WUS by DedicatedSignaling from a BS (eNB or gNB).

In Method 1-3, when UE sub-grouping of UEs is indicated by UE-specificdedicated signaling, a method to be applied is proposed.

In a specific method of applying Method 1-3, UE-specific dedicatedsignaling may be dedicated RRC signaling that a UE obtains during RRCconnection setup or in the RRC connected mode. For this purpose, a UEmay report information required for configuring UE sub-grouping (e.g., acoverage level, a type of service, a capability, and so on) on anNPUSCH.

In another specific method of applying Method 1-3, UE-specific dedicatedsignaling may be information that the UE obtains in a step for Msg2 orMsg4 of an RACH procedure (or random access procedure). For thispurpose, the UE may report information required for configuring UEsub-grouping (e.g., a coverage level, a type of service, a capability,and so on) in a step for Msg1 or Msg3.

[Method 1-4] Method of Performing UE Sub-Grouping for a WUS Based on theUsage of a Corresponding Channel Indicated by the WUS.

In Method 1-4, it is proposed that UE sub-grouping of UEs is appliedbased on a corresponding channel indicated by a WUS. The correspondingchannel refers to a channel about which the WUS indicates information.

Capability Report

In a specific method of applying Method 1-4, for UE sub-grouping, the UEmay report its capability for a corresponding channel supported by theUE. After the UE reports the capability, UE sub-grouping may beperformed only when the BS provides the UE with additional signalinginformation. For example, the additional signaling information may bededicated signaling as proposed in Method 1-3 or information thatenables/disables WUS support for a specific corresponding channelobtainable in the RRC idle mode, such as an SIB.

UE Behavior and Corresponding Channel Identification)

In Method 1-4, after UE sub-grouping, the UE may monitor only a WUScorresponding to its UE sub-group. When the WUS indicates multiplecorresponding channels, the UE may identify information about acorresponding channel by comparing bit information included in asubsequent control channel or masked RNTIs, or may finally confirminformation about the corresponding channel on a data channel indicatedby the subsequent control channel.

Alternatively in Method 1-4, after the UE sub-grouping is determined,the UE may monitor all available WUSs that can be monitored,irrespective of a WUS corresponding to its UE sub-group and a UEsub-grouping capability. When a WUS indicates multiple correspondingchannels, the UE may distinguish the corresponding channels bydistinguishing WUS resources (e.g., time-domain, frequency-domain,and/or code-domain resources). In a characteristic example, the UE maysimultaneously monitor a WUS serving a purpose other than paging, whichis distinguishable by a sequence (and/or frequency) in a specific timeresource (e.g., a subframe period determined by a gap from a PO and amaximum duration) in which the UE monitors a WUS for paging. The UE maydetermine how a subsequent corresponding channel will be transmitted,based on a detected WUS.

Examples of Corresponding Channel in Method 1-4 Other than Paging DCI

In an example of Method 1-4, the defined corresponding channel may be aUL resource for a preconfigured UL transmission (e.g., semi-persistentscheduling (SPS)). A WUS for which UE sub-grouping has been performedmay be used for activating/deactivating the use of the preconfigured ULresource or indicating an ACK/NACK or a retransmission for thepreconfigured UL resource.

In an example of Method 1-4, the defined corresponding channel may be aDL resource for a preconfigured UL transmission (e.g., SPS). A WUS forwhich UE sub-grouping has been performed may be used to indicate whetherDCI providing information related to the preconfigured UL transmissionis transmitted.

In an example of Method 1-4, the defined corresponding channel may beDCI masked by a G-RNTI (or SC-RNTI) in single cell point to multipoint(SC-PTM). A WUS for which UE sub-grouping has been performed may be usedto indicate whether DCI masked by a G-RNTI (or SC-RNTI) is transmittedor whether a single cell multicast transport channel (SC-MTCH)(or singlecell multicast control channel (SC-MCCH)) has been modified. When a WUSindicates whether DCI masked by a G-RNTI is transmitted, different UEsub-groups may be configured in correspondence with different G-RNTIs.When both of DCI masked by an SC-RNTI and DCI masked by a G-RNTI aresubjected to UE sub-grouping, different UE sub-groups may be configuredin correspondence with the SC-RNTI and the G-RNTI.

In an example of Method 1-4, the defined corresponding channel may havea multi-TB transmission structure. A WUS for which UE sub-grouping hasbeen performed may be used to activate/deactivate the use of themulti-TB transmission structure. Alternatively, the WUS may be used toindicate whether a subsequent corresponding channel is in a DCI formatsupporting multi-TB transmission or a DCI format supporting single-TBtransmission. Multi-TB transmission refers to a transmission structurein which a plurality of traffic channels (e.g., (N)PDCCH or (N)PUSCH)are scheduled by one DCI (or a preconfigured resource without DCI).

[Method 1-5] Method of Performing UE Sub-Grouping for a WUS Only Basedon a Cell (or Carrier) for which a UE has Obtained UE Sub-GroupingInformation.

In Method 1-5, it is proposed UE sub-grouping is applied only to a cellfor which a UE has obtained UE sub-grouping information. In NB-IoT, whenUE sub-grouping information is provided carrier-specifically, the termcell may be replaced with carrier.

In a specific method of applying Method 1-5, when UE sub-grouping isapplied according to specific criteria (e.g., UE_ID, a coverage level,dedicated signaling, a corresponding channel, and so on), a UE mayperform a UE sub-grouping-related operation only for a cell for whichthe UE has been configured with UE sub-grouping information, skippingthe UE sub-grouping-related operation for a cell for which the UE hasnot been configured with UE sub-grouping information. The UE may notexpect a WUS-related operation until before obtaining UE sub-groupinginformation in an adjacent cell or a new cell, or may perform theWUS-related operation in a WUS resource (e.g., a WUS defined in Rel-15)which may be monitored UE-commonly irrespective of UE sub-groupingcriteria.

[Method 1-6] Method of Performing UE Sub-Grouping Based on a Time Passedafter the Last UL Transmission and/or DL Reception.

In Method 1-6, it is proposed that a UE is included in a specific UEsub-group based on a time of completing the last UL transmission and/orDL reception, and then switched to another UE sub-group a predeterminedtime later or skipping UE sub-grouping until before the next ULtransmission and/or DL reception is completed. The proposed method maybe useful when there is a low possibility that the UE will be pagedduring a predetermined time after transmitting or receiving traffic.

In a specific method for which Method 1-6 is applied, Method 1-6 may beapplied only to a case where the BS and the UE are capable of confirmingtransmission and reception of a channel to which the UL transmissionand/or the DL reception is directed. For example, this case maycorrespond to a case in which the UE and the BS exchange information asis done in the EDT, a case in which whether a specific channel has beenreceived may be feed backed through an HARQ-ACK channel, or a case of anRRC message.

[Method 1-7] Method of Hopping the Sub-Group Index of a UE.

In Method 1-7, it is proposed that when there is a fixed WUS resourcecorresponding to each sub-group index, the WUS sub-group index of a UEhops over time. This operation may be intended to prevent continuousperformance degradation caused by the use of a specific WUS resource ata UE, when there is a difference in feature or gain between WUSresources used for sub-grouping.

In a specific method of Method 1-7, the UE may determine that thesub-group index of a corresponding WUS hops in each PO. A selectedsub-group index may be maintained unchanged during a time period inwhich a WUS transmission starts and is repeated.

In a specific method of Method 1-7, when sub-group index hopping isdetermined by a system frame number (SFN), a parameter such asfloor(SFN/T) may be used to achieve hopping effects. In a characteristicexample, when a sub-group index is hopped every period of a DRX cycle,the value of T may be determined to be the value of the DRX cycle.Herein, floor( ) represents a floor function.

In an example of Method 1-7, when the UE_ID-based uniform distributionmethod proposed in Method 1-1 and sub-group index hopping are applied, asub-group index may be determined by Equation (Eq-1-7-a-MTC) for MTC,and Equation (Eq-1-7-a-NB) for NB-IoT

Alternatively, in an example of Method 1-7, when the UE_ID-basednon-uniform distribution method proposed in Method 1-1 and sub-groupindex hopping are applied, a sub-group index may be determined byEquation (Eq-1-7-b-MTC) for MTC, and Equation (Eq-1-7-b-NB) for NB-IoT

In Equations (Eq-1-7-a-MTC), (Eq-1-7-a-NB), (Eq-1-7-b-MTC), and(Eq-1-7-b-NB), is a parameter used to achieve sub-group index hoppingeffects, which is defined as a variable determined by a reference valuedistinguishable on the time axis. For example, when an SFN and a DRXcycle are used as references, it may be defined that β=floor(SFN/T) Forthe other parameters than β and operations, Equations (Eq-1-1-a-MTC),(Eq-1-1-a-NB), (Eq-1-1-b-MTC), and (Eq-1-1-b-NB) are used in the samemanner.

c _(g)=[floor(UE_ID/(N*N _(S) *N _(n)))+β]mod N _(SG)  (Eq-1-7-a-MTC)

c _(g)=[floor(UE_ID/(N*N _(S) *W))+β]mod N _(SG)  (Eq-1-7-a-NB)

[floor(UE_ID/(N*N _(S) *N _(n)))+β]mod W _(WUS) <W _(WUS)(0)+W_(WUS)(1)+ . . . +W _(WUS)(c _(g))  (Eq-1-7-b-MTC)

[floor(UE_ID/(N*N _(S) *W))+β]mod W _(WUS) <W _(WUS)(0)+W _(WUS)(1)+ . .. +W _(WUS)(c _(g))  (Eq-1-7-b-NB)

In another method to achieve the same effects as Method 1-7, a mappingrelationship between sub-group indexes and WUS resources may be changedover time, with the sub-group index of a UE fixed.

G.2 UE Sub-Grouping Configuration

The present disclosure proposes a method of configuring relatedinformation by a base station (BS) and operations performed by a userequipment (UE), to apply UE sub-grouping to WUS transmission andreception. One or a combination of two or more of the following Method2-1, Method 2-2, Method 2-3, or Method 2-4 may be used as a method ofconfiguring UE sub-grouping.

[Method 2-1] Unit of Applying UE Sub-Grouping Information

In Method 2-1, when UE sub-grouping is configured, a method ofdetermining a range to which the UE sub-grouping configuration isapplied and related operations are proposed.

In Method 2-1, a unit for which UE sub-grouping information isconfigured may be a cell. This may be intended to reduce signalingoverhead. Alternatively, when hopping is applied to a WUS, this may beintended to maintain the same WUS configuration irrespective of thetransmission position (e.g., narrowband or carrier) of the WUS.

In Method 2-1, a unit for which UE sub-grouping information isconfigured may be a carrier in NB-IoT. Because a WUS is repeated adifferent number of times, power boosting is available or unavailable,or a different number of resources are available in each carrier, acarrier may be set as the unit in order to control the type of UEsub-grouping or the number of UE sub-groups, or enable/disable UEsub-grouping in consideration of the difference. In MTC, the termcarrier may be replaced with narrowband. When frequency hopping isapplied between narrowbands, a UE sub-grouping criterion may bedetermined to be a narrowband carrying a corresponding channel indicatedby a WUS.

In Method 2-1, a unit for which UE sub-grouping is configured may be acorresponding channel indicated by a WUS. For example, when UEsub-grouping is applied to paging, a carrier (or narrowband) for whichUE sub-grouping is supported may be limited to a carrier carryingpaging. Alternatively, for example, when UE sub-grouping is applied toSC-PTM, SPS, or multi-TB transmission, UE sub-grouping may be performedonly on a carrier (or narrowband) in which a transmission and receptionstructure for each purpose is operated.

[Method 2-2] Method of Determining Whether UE Sub-Grouping is AppliedAccording to the Gap Capability of a UE.

In Method 2-2, it is proposed that UE sub-grouping configurations aredifferentiated according to the WUS-to-PO gap capabilities of UEs. AWUS-to-PO gap capability of a UE refers to a UE capability used todetermine the size of a gap configured between the ending subframe of aWUS and a PO and may be defined as in 3GPP TS 36.304 V15.0.0.

In a specific method of applying Method 2-2, a configuration related toUE sub-grouping may be independently set for each WUS-to-PO gapcapability. For example, a higher-layer signal carrying UEsub-grouping-related configuration information may be designed to havean independent field for each WUS-to-PO gap capability.

In a specific method of applying Method 2-2, UE sub-grouping may not beapplied to a UE having a specific WUS-to-PO gap capability. For example,UE sub-grouping may not be applied to a large gap-capable UE (e.g., a UEconfigurable with a WUS-to-PO gap of {1s, 2s} in an eDRX situation).Alternatively, in a contrary example, UE sub-grouping may not be appliedto a short gap-capable UE (e.g., a UE unconfigurable with the WUS-to-POgap of {1s, 2s} in the eDRX situation).

Considering that the implementation complexity and performance of a WUSdetector may be different according to a WUS-to-PO gap capability, themethod proposed in Method 2-2 may be intended to reduce an increase inUE complexity for UE sub-grouping or the degradation of WUS detectionperformance for a UE having a capability with a relatively lowrequirement (e.g., a larger cap capability). Alternatively, the methodmay be intended to reduce the degradation of WUS detection performancecaused by UE sub-grouping for a UE having a shorter gap capability, tosecure a sufficient time required to prepare for monitoring acorresponding channel after fast WUS detection.

[Method 2-3] Method of Determining Whether UE Sub-Grouping is AppliedAccording to the Size of a Gap Configured by a BS

In Method 2-3, it is proposed that UE sub-grouping configurations aredifferentiated according to a configured size of a WUS-to-PO gap. Thesize of a WUS-to-PO gap refers to the size of a gap configured betweenthe ending subframe of a WUS and a PO, and may be defined as in 3GPP TS36.304 V15.0.0.

That is, a gap mentioned in Method 2-3 may be a gap illustrated in theafore-described drawing (e.g., FIG. 25) illustrating a WUS timing.

In a specific method of applying Method 2-3, a configuration related toUE sub-grouping may be independently set for each WUS-to-PO gap size.For example, a BS may configure two or more gaps corresponding to onePO, and a higher-layer signal carrying UE sub-grouping-relatedconfiguration information may be designed to have an independent fieldfor each WUS-to-PO gap size.

In a specific method of applying Method 2-3, UE sub-grouping may not beapplied for a specific WUS-to-PO gap size. For example, UE sub-groupingmay not be applied to a larger gap (e.g., a gap size of {1s, 2s}configured in an eDRX situation). This is because for a larger gap, aseparate WUS receiver operating with low complexity may be applied, andin this case, the degradation of WUS performance caused by UEsub-grouping may be relatively serious. Alternatively, in a contraryexample, UE sub-grouping may not be applied to a shorter gap (e.g., aconfigured gap size of {40 ms, 80 ms, 160 ms, 240 ms}). This may beintended to secure an extra spacing by shortening an actual transmissionduration instead of performing UE sub-grouping because there is arelative shortage of an extra spacing between a WUS and a PO.

In another specific method of applying Method 2-3, UE sub-grouping maybe applied depending on whether a UE performs an eDRX operation. Forexample, UE sub-grouping may not be applied in eDRX. This is intended toprevent the degradation of WUS detection performance caused by UEsub-grouping because missed paging may lead to a fatal delay to the nextpaging transmittable time in eDRX. Alternatively, in another method forthe same purpose, a separate configuration may be used, whichdistinguishes UE sub-grouping for an eDRX operation from UE sub-groupingfor a DRX operation.

[Method 2-4] Method of Reporting Information Related to its Mobility forUE Sub-Grouping by a UE

In Method 2-4, it is proposed that a UE reports information related toits mobility for UE sub-grouping. The mobility may mean a change in acommunication channel environment, caused by movement of the UE toanother physical position.

In a specific method of applying Method 2-4, the UE may autonomouslydetermine whether to perform UE sub-grouping based on its mobility andreport the determination to the BS. In the presence of a UE sub-groupingrequest report based on the mobility of the UE, the BS may transmit aWUS by applying a UE sub-grouping-related operation for the UE. The UEmay identify that the UE sub-grouping operation is possible at atransmission position at which the UE expects a WUS, and perform the UEsub-grouping-related operation after transmitting a UEsub-groping-capable report based on its mobility to the BS.Alternatively, the UE may start UE sub-grouping after receiving separateconfirmation signaling for the report. In this method, (1) a referencepredetermined in a standard or (2) a reference configurable byhigher-layer signaling from the BS may be used as reference mobility fordetermining whether to perform UE sub-grouping by the UE.

In a specific method of applying Method 2-4, the UE may reportinformation about its mobility to the BS, and the BS may determinewhether UE sub-grouping is to be performed based on the report andconfigure the determination result for the UE. After reporting theinformation about its measured mobility, the UE may expect signalingindicating whether UE sub-grouping is to be performed from the BS. Uponacquisition of information related to UE sub-grouping, the UE maydetermine whether to apply UE sub-grouping according to the receivedinformation. Whether the UE fails to acquire the information about UEsub-grouping, the UE may monitor a common WUS (e.g., a WUS identifiableby all WUS-capable UEs irrespective of UE sub-groups), without expectinga UE sub-grouping-related operation.

Characteristically in applying Method 2-4, when the BS operates UEsub-grouping based on a plurality of criteria or purposes, themobility-based report may be restrictively reflected in specific UEsub-grouping criteria. For example, because the coverage level of a UEwith mobility may change over time, it may be determined whethercoverage level-based UE sub-grouping is to be applied according to amobility-based report. In contrast, a criterion such as UE_ID isapplicable without much relation to the mobility of a UE, UE_ID-based UEsub-grouping may always be applied irrespective of the mobility-basedreport information.

G.3 Flowcharts of Methods of the Present Disclosure

FIG. 26 is an exemplary flowchart illustrating a method of the presentdisclosure. While the example of FIG. 26 is described in the context ofa user equipment (UE), an operation corresponding to the operationillustrated in FIG. 26 may be performed by a base station (BS). Asdescribed before, Method 1-1 to Method 1-7 of the present disclosure maybe performed independently, or in combination of one or more of them.

In step S2602, a UE may determine a WUS resource based on UEsub-grouping for a WUS.

For example, in step S2602, the UE may determine index information(e.g., UE sub-group index information c_(g)) indicating a WUS resourcebased on identification information (e.g., UE_ID) of the UE anddetermine a WUS resource related to a sub-group of the UE based on thedetermined index information (e.g., refer to the description of Method1-1). For example, when the UE supports MTC, the index informationindicating the WUS resource may be determined based on theidentification information (e.g., UE_ID) of the UE, parameters (e.g., Nand N_(s)) related to a DRX cycle of the UE, information (e.g., N_(n))about the number of paging narrowbands, and information (e.g., N_(SG))about the number of UE groups for the WUS (e.g., refer to Eq-1-1-a-MTC).When the UE supports MTC, the index information indicating the WUSresource may be determined based on the identification information(e.g., UE_ID) of the UE, the parameters (e.g., N and N_(s)) related tothe DRX cycle of the UE, the information (e.g., N_(n)) about the numberof paging narrowbands, and information (e.g., W_(WUS)) about the sum ofweights of all UE sub-groups (e.g., refer to Eq-1-1-b-MTC). In anotherexample, when the UE supports NB-IoT, the index information indicatingthe WUS resource may be determined based on the identificationinformation (e.g., UE_ID) of the UE, the parameters (e.g., N and N_(s))related to the DRX cycle of the UE, information about the sum (e.g., W)of weights of paging carriers, and the information (e.g., N_(SG)) aboutthe number of UE groups for the WUS (e.g., refer to Eq-1-1-a-NB).Alternatively, when the UE supports NB-IoT, the index informationindicating the WUS resource may be determined based on theidentification information (e.g., UE_ID) of the UE, the parameters(e.g., N and N_(s)) related to the DRX cycle of the UE, the informationabout the sum (e.g., W) of the weights of the paging carriers, and theinformation (e.g., W_(WUS)) about the sum of the weights of all UEsub-groups (e.g., refer to Eq-1-1-b-NB).

Independently or additionally, the UE may determine a WUS resource basedon a coverage level (e.g., refer to Method 1-2) in step S2602. Forexample, the coverage level of a UE refers to the state of a wirelesschannel environment in which the UE is placed. In a characteristicexample, a measurement such as a UE-measured RSRP/RSRQ or a repetitionnumber used for the UE to transmit a UL channel or receive a DL channelmay be used as the coverage level.

Independently or additionally, in step S2602, the UE may receiveUE-specific dedicated signaling from the BS. When the dedicatedsignaling indicates UE sub-grouping, the UE may report information forconfiguring UE sub-grouping (e.g., a coverage level, a type of service,a capability, and so on) via a PUSCH (e.g., NPUSCH), Msg1, or Msg3(e.g., refer to Method 1-3).

Independently or additionally, in step S2602, the UE may determine a WUSresource only for a cell (or carrier) for which the UE has acquired UEsub-grouping information, based on UE sub-grouping (e.g., refer toMethod 1-5).

Independently or additionally, in step S2602, the UE may determine a UEsub-group and a WUS resource corresponding to the UE sub-group, based ona time of completing the last UL transmission and/or DL reception (e.g.,refer to Method 1-6).

Independently or additionally, in step S2602, UE sub-group indexinformation and/or a WUS resource corresponding to the UE sub-groupindex information may hop over time by the UE (e.g., refer to Method1-7). More specifically, the UE sub-group index information and/or theWUS resource corresponding to the UE sub-group index information may bedetermined based on an SFN (e.g., refer to Method 1-7).

Independently or additionally, the WUS may be used to indicatetransmission and reception of a channel as well as a paging signal. TheUE may determine a WUS resource based on the channel (e.g.,corresponding channel) indicated by the WUS (e.g., refer to Method 1-4).In this case, the UE may report a capability for a channel (e.g.,corresponding channel) supported for UE sub-grouping to the BS, and theBS may indicate to the UE to determine a WUS resource based on UEsub-grouping by separate signaling information (e.g., refer to Method1-4).

In step S2604, the UE may monitor a WUS based on the WUS resource. Forexample, the UE may monitor the WUS based on the index information(e.g., the UE sub-group index information c_(g)) determined in stepS2602 (or based on the WUS resource indicated by the index information)(e.g., refer to Method 1-1). Alternatively, for example, the UE maymonitor the WUS based on a WUS resource corresponding to the coveragelevel determined in step S2602 (e.g., refer to Method 1-2).

Independently or additionally, when the index information indicating aWUS resource (e.g., the UE sub-group index information c_(g)) (and/orthe WUS resource corresponding to the index information) hops over time,the UE may monitor the WUS based on the hopped index information (and/orthe WUS resource corresponding to the hopped index information) (e.g.,refer to Method 1-7).

Upon detection of the WUS in step S2604, the UE may receive a pagingsignal in a PO related to the detected WUS in step S2606. As describedbefore, the WUS may be used to indicate whether a paging signal will betransmitted and received, and also whether a channel (e.g.,corresponding channel) other than the paging signal will be transmittedand received (e.g., refer to Method 1-4). For example, the channel(e.g., corresponding channel) related to the WUS may be a UL resourcefor a preconfigured UL transmission (e.g., SPS), a DL resource for apreconfigured DL transmission (e.g., SPS), DCI masked by a G-RNTI (orSC-RNTI) in SC-PTM, an SC-MTCH (or SC-MCCH), and/or a channel of amulti-TB transmission structure (refer to Method 1-4). When multiplechannels (e.g., corresponding channels) are related to the WUS, the UEmay determine and receive the channel related to the WUS based on bitinformation included in a control channel, an RNTI by which the controlchannel is masked, information received on a data channel indicated bythe control channel, and/or the WUS resource (e.g., refer to Method1-4).

When the UE fails to detect the WUS in step S2604, the UE may skipreception of a paging signal related to the WUS in step S2606.

The UE (which has received the WUS) may additionally perform theafore-described DRX operation and/or cell reselection operation.

The operations described in Method 1-1 to Method 1-7 and/or acombination thereof may be performed in the steps of FIG. 26, and thedescription of Method 1-1 to Method 1-7 is incorporated by reference inthe description of FIG. 26 in its entirety.

G.4 Communication System and Devices to which the Present Disclosure isApplied

Various descriptions, functions, procedures, proposals, methods, and/orflowcharts of the present disclosure may be applied to, but not limitedto, various fields requiring wireless communication/connection (e.g.,5G) among devices.

Hereinafter, they will be described in more detail with reference to thedrawings. In the following drawings/description, the same referencenumerals may denote the same or corresponding hardware blocks, softwareblocks, or functional blocks, unless specified otherwise.

FIG. 27 illustrates a communication system 1 applied to the presentdisclosure.

Referring to FIG. 27, the communication system 1 applied to the presentdisclosure includes wireless devices, base stations (BSs), and anetwork. The wireless devices refer to devices performing communicationby radio access technology (RAT) (e.g., 5G New RAT (NR) or LTE), whichmay also be called communication/radio/5G devices. The wireless devicesmay include, but no limited to, a robot 100 a, vehicles 100 b-1 and 100b-2, an extended reality (XR) device 100 c, a hand-held device 100 d, ahome appliance 100 e, an IoT device 100 f, and an artificialintelligence (AI) device/server 400. For example, the vehicles mayinclude a vehicle equipped with a wireless communication function, anautonomous driving vehicle, and a vehicle capable of performingvehicle-to-vehicle (V2V) communication. The vehicles may include anunmanned aerial vehicle (UAV) (e.g., a drone). The XR device may includean augmented reality (AR)/virtual reality (VR)/mixed reality (MR)device, and may be implemented in the form of a head-mounted device(HMD), a head-up display (HUD) mounted in a vehicle, a television (TV),a smartphone, a computer, a wearable device, a home appliance, a digitalsignage, a vehicle, a robot, and so on. The hand-held device may includea smartphone, a smartpad, a wearable device (e.g., a smartwatch or smartglasses), and a computer (e.g., a laptop). The home appliance mayinclude a TV, a refrigerator, and a washing machine. The IoT device mayinclude a sensor and a smart meter. For example, the BSs and the networkmay be implemented as wireless devices, and a specific wireless device200 a may operate as a BS/network node for other wireless devices.

The wireless devices 100 a to 100 f may be connected to the network 300via the BSs 200. An AI technology may be applied to the wireless devices100 a to 100 f, and the wireless devices 100 a to 100 f may be connectedto the AI server 400 via the network 300. The network 300 may beconfigured by using a 3G network, a 4G (e.g., LTE) network, or a 5G(e.g., NR) network. Although the wireless devices 100 a to 100 f maycommunicate with each other through the BSs 200/network 300, thewireless devices 100 a to 100 f may perform direct communication (e.g.,sidelink communication) with each other without intervention of theBSs/network. For example, the vehicles 100 b-1 and 100 b-2 may performdirect communication (e.g. V2V/vehicle-to-everything (V2X)communication). The IoT device (e.g., a sensor) may perform directcommunication with other IoT devices (e.g., sensors) or other wirelessdevices 100 a to 100 f.

Wireless communication/connections 150 a, 150 b, or 150 c may beestablished between the wireless devices 100 a to 100 f and the BSs 200,or between the BSs 200. Herein, the wireless communication/connectionsmay be established through various RATs (e.g., 5G NR) such as UL/DLcommunication 150 a, sidelink communication 150 b (or, D2Dcommunication), or inter-BS communication 150 c (e.g. relay, integratedaccess backhaul (IAB)). A wireless device and a BS/a wireless devices,and BSs may transmit/receive radio signals to/from each other throughthe wireless communication/connections 150 a, 150 b, and 150 c. To thisend, at least a part of various configuration information configuringprocesses, various signal processing processes (e.g., channelencoding/decoding, modulation/demodulation, and resourcemapping/demapping), and resource allocating processes, fortransmitting/receiving radio signals, may be performed based on thevarious proposals of the present disclosure.

FIG. 28 illustrates wireless devices applicable to the presentdisclosure.

Referring to FIG. 28, a first wireless device 100 and a second wirelessdevice 200 may transmit radio signals through a variety of RATs (e.g.,LTE and NR). Herein, {the first wireless device 100 and the secondwireless device 200} may correspond to {the wireless devices 100 a to100 f and the BSs 200} and/or {the wireless devices 100 a to 100 f andthe wireless devices 100 a to 100 f} of FIG. 27.

The first wireless device 100 may include at least one processor 102 andat least one memory 104, and may further include at least onetransceiver 106 and/or at least one antenna 108. The processor 102 maycontrol the memory 104 and/or the transceiver 106 and may be configuredto implement the descriptions, functions, procedures, proposals,methods, and/or operational flowcharts disclosed in this document. Forexample, the processor 102 may process information within the memory 104to generate first information/signal and then transmit a radio signalincluding the first information/signal through the transceiver 106. Theprocessor 102 may receive a radio signal including secondinformation/signal through the transceiver 106 and then storeinformation obtained by processing the second information/signal in thememory 104. The memory 104 may be coupled to the processor 102 and storevarious types of information related to operations of the processor 102.For example, the memory 104 may store software code including commandsfor performing a part or all of processes controlled by the processor102 or for performing the descriptions, functions, procedures,proposals, methods, and/or operational flowcharts disclosed in thisdocument. Herein, the processor 102 and the memory 104 may be a part ofa communication modem/circuit/chip designed to implement an RAT (e.g.,LTE or NR). The transceiver 106 may be coupled to the processor 102 andtransmit and/or receive radio signals through the at least one antenna108. The transceiver 106 may include a transmitter and/or a receiver.The transceiver 106 may be interchangeably used with an RF unit. In thepresent disclosure, a wireless device may refer to a communicationmodem/circuit/chip.

The second wireless device 200 may include at least one processor 202and at least one memory 204, and may further include at least onetransceiver 206 and/or at least one antenna 208. The processor 202 maycontrol the memory 204 and/or the transceiver 206 and may be configuredto implement the descriptions, functions, procedures, proposals,methods, and/or operational flowcharts disclosed in this document. Forexample, the processor 202 may process information within the memory 204to generate third information/signal and then transmit a radio signalincluding the third information/signal through the transceiver 206. Theprocessor 202 may receive a radio signal including fourthinformation/signal through the transceiver 206 and then storeinformation obtained by processing the fourth information/signal in thememory 204. The memory 204 may be coupled to the processor 202 and storevarious types of information related to operations of the processor 202.For example, the memory 204 may store software code including commandsfor performing a part or all of processes controlled by the processor202 or for performing the descriptions, functions, procedures,proposals, methods, and/or operational flowcharts disclosed in thisdocument. Herein, the processor 202 and the memory 204 may be a part ofa communication modem/circuit/chip designed to implement an RAT (e.g.,LTE or NR). The transceiver 206 may be coupled to the processor 202 andtransmit and/or receive radio signals through the at least one antenna208. The transceiver 206 may include a transmitter and/or a receiver.The transceiver 206 may be interchangeably used with an RF unit. In thepresent disclosure, a wireless device may refer to a communicationmodem/circuit/chip.

Hereinafter, hardware elements of the wireless devices 100 and 200 willbe described in greater detail. One or more protocol layers may beimplemented by, but not limited to, one or more processors 102 and 202.For example, the one or more processors 102 and 202 may implement one ormore layers (e.g., functional layers such as PHY, MAC, RLC, PDCP, RRC,and SDAP). The one or more processors 102 and 202 may generate one ormore protocol data units (PDUs) and/or one or more service data units(SDUs) according to the descriptions, functions, procedures, proposals,methods, and/or operational flowcharts disclosed in this document. Theone or more processors 102 and 202 may generate messages, controlinformation, data, or information according to the descriptions,functions, procedures, proposals, methods, and/or operational flowchartsdisclosed in this document. The one or more processors 102 and 202 maygenerate signals (e.g., baseband signals) including PDUs, SDUs,messages, control information, data, or information according to thedescriptions, functions, procedures, proposals, methods, and/oroperational flowcharts disclosed in this document and provide thegenerated signals to the one or more transceivers 106 and 206. The oneor more processors 102 and 202 may receive the signals (e.g., basebandsignals) from the one or more transceivers 106 and 206 and acquire thePDUs, SDUs, messages, control information, data, or informationaccording to the descriptions, functions, procedures, proposals,methods, and/or operational flowcharts disclosed in this document.

The one or more processors 102 and 202 may be referred to ascontrollers, microcontrollers, microprocessors, or microcomputers. Theone or more processors 102 and 202 may be implemented in hardware,firmware, software, or a combination thereof. For example, one or moreapplication specific integrated circuits (ASICs), one or more digitalsignal processors (DSPs), one or more digital signal processing devices(DSPDs), one or more programmable logic devices (PLDs), or one or morefield programmable gate arrays (FPGAs) may be included in the one ormore processors 102 and 202. The descriptions, functions, procedures,proposals, methods, and/or operational flowcharts disclosed in thisdocument may be implemented in firmware or software, which may beconfigured to include modules, procedures, or functions. Firmware orsoftware configured to perform the descriptions, functions, procedures,proposals, methods, and/or operational flowcharts disclosed in thisdocument may be included in the one or more processors 102 and 202, ormay be stored in the one or more memories 104 and 204 and executed bythe one or more processors 102 and 202. The descriptions, functions,procedures, proposals, methods, and/or operational flowcharts disclosedin this document may be implemented as code, instructions, and/or a setof instructions in firmware or software.

The one or more memories 104 and 204 may be coupled to the one or moreprocessors 102 and 202 and store various types of data, signals,messages, information, programs, code, instructions, and/or commands.The one or more memories 104 and 204 may be configured as read-onlymemories (ROMs), random access memories (RAMs), electrically erasableprogrammable read-only memories (EPROMs), flash memories, hard drives,registers, cash memories, computer-readable storage media, and/orcombinations thereof. The one or more memories 104 and 204 may belocated at the interior and/or exterior of the one or more processors102 and 202. The one or more memories 104 and 204 may be coupled to theone or more processors 102 and 202 through various technologies such aswired or wireless connection.

The one or more transceivers 106 and 206 may transmit user data, controlinformation, and/or radio signals/channels, mentioned in the methodsand/or operational flowcharts of this document, to one or more otherdevices. The one or more transceivers 106 and 206 may receive user data,control information, and/or radio signals/channels, mentioned in thedescriptions, functions, procedures, proposals, methods, and/oroperational flowcharts disclosed in this document, from one or moreother devices. For example, the one or more transceivers 106 and 206 maybe coupled to the one or more processors 102 and 202 and transmit andreceive radio signals. For example, the one or more processors 102 and202 may control the one or more transceivers 106 and 206 to transmituser data, control information, or radio signals to one or more otherdevices. The one or more processors 102 and 202 may control the one ormore transceivers 106 and 206 to receive user data, control information,or radio signals from one or more other devices. The one or moretransceivers 106 and 206 may be coupled to the one or more antennas 108and 208 and configured to transmit and receive user data, controlinformation, and/or radio signals/channels, mentioned in thedescriptions, functions, procedures, proposals, methods, and/oroperational flowcharts disclosed in this document, through the one ormore antennas 108 and 208. In this document, the one or more antennasmay be a plurality of physical antennas or a plurality of logicalantennas (e.g., antenna ports). The one or more transceivers 106 and 206may convert received radio signals/channels etc. from RF band signalsinto baseband signals in order to process received user data, controlinformation, radio signals/channels, etc. using the one or moreprocessors 102 and 202. The one or more transceivers 106 and 206 mayconvert the user data, control information, radio signals/channels, etc.processed using the one or more processors 102 and 202 from the baseband signals into the RF band signals. To this end, the one or moretransceivers 106 and 206 may include (analog) oscillators and/orfilters.

FIG. 29 illustrates another example of wireless devices applied to thepresent disclosure. The wireless devices may be implemented in variousforms according to use-cases/services (refer to FIG. 27).

Referring to FIG. 29, wireless devices 100 and 200 may correspond to thewireless devices 100 and 200 of FIG. 28 and may be configured as variouselements, components, units/portions, and/or modules. For example, eachof the wireless devices 100 and 200 may include a communication unit110, a control unit 120, a memory unit 130, and additional components140. The communication unit may include a communication circuit 112 andtransceiver(s) 114. For example, the communication circuit 112 mayinclude the one or more processors 102 and 202 and/or the one or morememories 104 and 204 of FIG. 28. For example, the transceiver(s) 114 mayinclude the one or more transceivers 106 and 206 and/or the one or moreantennas 108 and 208 of FIG. 28. The control unit 120 is electricallycoupled to the communication unit 110, the memory unit 130, and theadditional components 140 and provides overall control to operations ofthe wireless devices. For example, the control unit 120 may control anelectric/mechanical operation of the wireless device based onprograms/code/commands/information stored in the memory unit 130. Thecontrol unit 120 may transmit the information stored in the memory unit130 to the outside (e.g., other communication devices) via thecommunication unit 110 through a wireless/wired interface or store, inthe memory unit 130, information received through the wireless/wiredinterface from the outside (e.g., other communication devices) via thecommunication unit 110.

The additional components 140 may be configured in various mannersaccording to the types of wireless devices. For example, the additionalcomponents 140 may include at least one of a power unit/battery, aninput/output (I/O) unit, a driver, and a computing unit. The wirelessdevice may be configured as, but not limited to, the robot (100 a ofFIG. 27), the vehicles (100 b-1 and 100 b-2 of FIG. 27), the XR device(100 c of FIG. 27), the hand-held device (100 d of FIG. 27), the homeappliance (100 e of FIG. 27), the IoT device (100 f of FIG. 27), adigital broadcasting terminal, a hologram device, a public safetydevice, an MTC device, a medicine device, a FinTech device (or a financedevice), a security device, a climate/environment device, the AIserver/device (400 of FIG. 27), the BSs (200 of FIG. 27), a networknode, etc. The wireless device may be mobile or fixed according to ause-case/service.

In FIG. 29, all of the various elements, components, units/portions,and/or modules in the wireless devices 100 and 200 may be coupled toeach other through a wired interface or at least a part thereof may bewirelessly coupled to each other through the communication unit 110. Forexample, in each of the wireless devices 100 and 200, the control unit120 and the communication unit 110 may be coupled wiredly, and thecontrol unit 120 and first units (e.g., 130 and 140) may be wirelesslycoupled through the communication unit 110. Each element, component,unit/portion, and/or module within the wireless devices 100 and 200 mayfurther include one or more elements. For example, the control unit 120may be configured as a set of one or more processors. For example, thecontrol unit 120 may be configured as a set of a communication controlprocessor, an application processor, an electronic control unit (ECU), agraphical processing unit, and a memory control processor. In anotherexample, the memory unit 130 may be configured as a random access memory(RAM), a dynamic RAM (DRAM), a read only memory (ROM), a flash memory, avolatile memory, a non-volatile memory, and/or a combination thereof.

An implementation example of FIG. 29 will be described in detail withreference to the drawings.

FIG. 30 illustrates a portable device applied to the present disclosure.The portable device may include a smartphone, a smartpad, a wearabledevice (e.g., a smart watch and smart glasses), and a portable computer(e.g., a laptop). The portable device may be referred to as a mobilestation (MS), a user terminal (UT), a mobile subscriber station (MSS), asubscriber station (SS), an advanced mobile station (AMS), or a wirelessterminal (WT).

Referring to FIG. 30, a portable device 100 may include an antenna unit108, a communication unit 110, a control unit 120, a power supply unit140 a, an interface unit 140 b, and an I/O unit 140 c. The antenna unit108 may be configured as a part of the communication unit 110. Theblocks 110 to 130/140 a to 140 c correspond to the blocks 110 to 130/140of FIG. 29, respectively.

The communication unit 110 may transmit and receive signals (e.g., dataand control signals) to and from another wireless device and a BS. Thecontrol unit 120 may perform various operations by controlling elementsof the portable device 100. The control unit 120 may include anapplication processor (AP). The memory unit 130 may storedata/parameters/programs/code/commands required for operation of theportable device 100.

Further, the memory unit 130 may store input/output data/information.The power supply unit 140 a may supply power to the portable device 100,and include a wired/wireless charging circuit and a battery. Theinterface unit 140 b may include various ports (e.g., an audio I/O portand a video I/O port) for connectivity to external devices The I/O unit140 c may acquire information/signals (e.g., touch, text, voice, images,and video) input by a user, and store the acquired information/signalsin the memory unit 130. The communication unit 110 may receive or outputvideo information/signal, audio information/signal, data, and/orinformation input by the user. The I/O unit 140 c may include a camera,a microphone, a user input unit, a display 140 d, a speaker, and/or ahaptic module.

For example, for data communication, the I/O unit 140 c may acquireinformation/signals (e.g., touch, text, voice, images, and video)received from the user and store the acquired information/signal sin thememory unit 130. The communication unit 110 may convert theinformation/signals to radio signals and transmit the radio signalsdirectly to another device or to a BS. Further, the communication unit110 may receive a radio signal from another device or a BS and thenrestore the received radio signal to original information/signal. Therestored information/signal may be stored in the memory unit 130 andoutput in various forms (e.g., text, voice, an image, video, and ahaptic effect) through the I/O unit 140 c.

FIG. 31 illustrates a vehicle or an autonomous driving vehicle appliedto the present disclosure. The vehicle or autonomous driving vehicle maybe configured as a mobile robot, a car, a train, a manned/unmannedaerial vehicle (AV), a ship, or the like.

Referring to FIG. 31, a vehicle or autonomous driving vehicle 100 mayinclude an antenna unit 108, a communication unit 110, a control unit120, a driving unit 140 a, a power supply unit 140 b, a sensor unit 140c, and an autonomous driving unit 140 d. The antenna unit 108 may beconfigured as a part of the communication unit 110. The blocks110/130/140 a to 140 d correspond to the blocks 110/130/140 of FIG. 29,respectively.

The communication unit 110 may transmit and receive signals (e.g., dataand control signals) to and from external devices such as othervehicles, BSs (e.g., gNBs and road side units), and servers. The controlunit 120 may perform various operations by controlling elements of thevehicle or the autonomous driving vehicle 100. The control unit 120 mayinclude an ECU. The driving unit 140 a may enable the vehicle or theautonomous driving vehicle 100 to travel on a road. The driving unit 140a may include an engine, a motor, a powertrain, a wheel, a brake, asteering device, and so on. The power supply unit 140 b may supply powerto the vehicle or the autonomous driving vehicle 100 and include awired/wireless charging circuit, a battery, and so on. The sensor unit140 c may acquire vehicle state information, ambient environmentinformation, user information, and so on. The sensor unit 140 c mayinclude an inertial measurement unit (IMU) sensor, a collision sensor, awheel sensor, a speed sensor, a slope sensor, a weight sensor, a headingsensor, a position module, a vehicle forward/backward sensor, a batterysensor, a fuel sensor, a tire sensor, a steering sensor, a temperaturesensor, a humidity sensor, an ultrasonic sensor, an illumination sensor,a pedal position sensor, and so on. The autonomous driving unit 140 dmay implement a technology for maintaining a lane on which a vehicle isdriving, a technology for automatically adjusting speed, such asadaptive cruise control, a technology for autonomously traveling along adetermined path, a technology for traveling by automatically setting apath, when a destination is set, and the like.

For example, the communication unit 110 may receive map data, trafficinformation data, and so on from an external server. The autonomousdriving unit 140 d may generate an autonomous driving path and a drivingplan from the obtained data. The control unit 120 may control thedriving unit 140 a such that the vehicle or autonomous driving vehicle100 may move along the autonomous driving path according to the drivingplan (e.g., speed/direction control). In the middle of autonomousdriving, the communication unit 110 may aperiodically/periodicallyacquire recent traffic information data from the external server andacquire surrounding traffic information data from neighboring vehicles.In the middle of autonomous driving, the sensor unit 140 c may obtainvehicle state information and/or ambient environment information. Theautonomous driving unit 140 d may update the autonomous driving path andthe driving plan based on the newly obtained data/information. Thecommunication unit 110 may transmit information about a vehicleposition, the autonomous driving path, and/or the driving plan to theexternal server. The external server may predict traffic informationdata using AI technology or the like, based on the information collectedfrom vehicles or autonomous driving vehicles and provide the predictedtraffic information data to the vehicles or the autonomous drivingvehicles.

FIG. 32 illustrates an exemplary vehicle applied to the presentdisclosure. The vehicle may be configured as a transportation means, atrain, an aircraft, a ship, or the like.

Referring to FIG. 32, a vehicle 100 may include a communication unit110, a control unit 120, a memory unit 130, an I/O unit 140 a, and apositioning unit 140 b. The blocks 110 to 130/140 a and 140 b correspondto the blocks 110 to 130/140 of FIG. 29.

The communication unit 110 may transmit and receive signals (e.g., data,control signals, and so on) to and from external devices such as othervehicles or a BS. The control unit 120 may perform various operations bycontrolling the components of the vehicle 100. The memory unit 130 maystore data/parameters/programs/code/commands supporting variousfunctions of the vehicle 100. The I/O unit 140 a may output an AR/VRobject based on information in the memory unit 130. The I/O unit 140 amay include an HUD. The positioning unit 140 b may acquire positioninformation about the vehicle 100. The position information may includeabsolute position information, information about a position within alane, acceleration information, information about a position relative toa neighbor vehicle, and so on of the vehicle 100. The positioning unit140 b may include a GPS and various sensors.

For example, the communication unit 110 of the vehicle 100 may receivemap information and traffic information from an external server andstore the received information in the memory unit 130. The positioningunit 140 b may acquire vehicle position information through the GPS andvarious sensors and store the acquired vehicle position information inthe memory unit 130. The control unit 120 may generate a virtual objectbased on the map information, traffic information, and vehicle positioninformation, and the I/O unit 140 a may display the generated virtualobject on a window in the vehicle (140 m and 140 n). Further, thecontrol unit 120 may determine whether the vehicle 100 is travelingnormally within a lane based on the vehicle position information. Whenthe vehicle 100 is abnormally outside the lane, the control unit 120 maydisplay a warning on a window in the vehicle via the I/O unit 140 a.Further, the control unit 130 may broadcast a warning message about theabnormal driving to neighboring vehicles. Under circumstances, thecontrol unit 120 may transmit position information about the vehicle andinformation about a driving/vehicle abnormality to an authority throughthe communication unit 110.

The embodiments of the present disclosure described hereinbelow arecombinations of elements and features of the present disclosure. Theelements or features may be considered selective unless otherwisementioned. Each element or feature may be practiced without beingcombined with other elements or features. Further, an embodiment of thepresent disclosure may be constructed by combining parts of the elementsand/or features. Operation orders described in embodiments of thepresent disclosure may be rearranged. Some constructions or features ofany one embodiment may be included in another embodiment and may bereplaced with corresponding constructions or features of anotherembodiment. It is obvious to those skilled in the art that claims thatare not explicitly cited in each other in the appended claims may bepresented in combination as an embodiment of the present disclosure orincluded as a new claim by a subsequent amendment after the applicationis filed.

The present disclosure is applicable to wireless communication devicessuch as a user equipment (UE) and a base station (BS) operating invarious wireless communication systems including 3GPP LTE/LTE-A/5G (orNew RAT (NR)).

What is claimed is:
 1. A method for receiving a paging signal by a userequipment (UE) in a wireless communication system supporting NarrowBandInternet of Things (NB-IoT), the method comprising: determining indexinformation indicating a wake up signal (WUS) group for the UE, whereina WUS resource for the UE is selected based on the determined indexinformation; and monitoring a WUS for the UE based on the selected WUSresource, wherein the index information indicating the WUS group for theUE is determined based on identification information of the UE,parameters related to a discontinuous reception (DRX) cycle of the UE, asum of weights for paging carriers, and information about a number of UEgroups for the WUS.
 2. The method of claim 1, wherein the indexinformation indicating the WUS group for the UE is determined based onthe following equation,c _(g)=floor(UE_ID/(N*N _(S) *W))mod N _(SG) where c_(g) represents theindex information indicating the WUS group for the UE, UE_ID representsthe identification information of the UE, N and N_(s) represent theparameters related to the DRX cycle of the UE, W represents the sum ofthe weights for paging carriers, and N_(SG) represents the informationabout the number of UE groups for the WUS.
 3. The method of claim 2,wherein the UE_ID is determined based on international mobile subscriberidentity (IMSI) information of the UE, wherein N is determined based onmin(T, nB) and N_(s) is determined based on max(1, nB/T) where Trepresents the DRX cycle of the UE, nB is indicated through systeminformation, min(A, B) represents a smaller value among A and B, andmax(A, B) represents a larger value among A and B, and wherein theweights for paging carriers are determined based on the systeminformation.
 4. The method of claim 1, wherein the WUS resource includesa resource in at least one of a time domain, a frequency domain, or acode domain.
 5. The method of claim 1, further comprising: based ondetecting the WUS, receiving the paging signal in a paging occasionrelated to the WUS.
 6. The method of claim 1, wherein the indexinformation indicating the WUS group for the UE hops over time.
 7. Themethod of claim 6, wherein a hopping pattern for the index informationindicating the WUS group for the UE is determined based on a systemframe number (SFN).
 8. A user equipment (UE) configured to receive apaging signal in a wireless communication system supporting NarrowBandInternet of Things (NB-IoT), the UE comprising: a radio frequency (RF)transceiver; and a processor operatively coupled to the RF transceiver,wherein the processor is configured to determine index informationindicating a wake-up signal (WUS) group for the UE, wherein a WUSresource for the UE is selected based on the determined indexinformation, and to control the RF transceiver to monitor a WUS for theUE based on the selected WUS resource, and wherein the index informationindicating the WUS group for the UE is determined based onidentification information of the UE, parameters related to adiscontinuous reception (DRX) cycle of the UE, a sum of weights forpaging carriers, and information about a number of UE groups for theWUS.
 9. The UE of claim 8, wherein the index information indicating theWUS group for the UE is determined based on the following equation,c _(g)=floor(UE_ID/(N*N _(S) *W))mod N _(SG) where c_(g) represents theindex information indicating the WUS group for the UE, UE_ID representsthe identification information of the UE, N and N_(s) represent theparameters related to the DRX cycle of the UE, W represents the sum ofthe weights for paging carriers, and N_(SG) represents the informationabout the number of UE groups for the WUS.
 10. The UE of claim 9,wherein the UE_ID is determined based on international mobile subscriberidentity (IMSI) information of the UE, wherein N is determined based onmin(T, nB) and N_(s) is determined based on max(1, nB/T) where Trepresents the DRX cycle of the UE, nB is indicated through systeminformation, min(A, B) represents a smaller value among A and B, andmax(A, B) represents a larger value among A and B, and wherein theweights for paging carriers are determined based on the systeminformation.
 11. The UE of claim 8, wherein the WUS resource includes aresource in at least one of a time domain, a frequency domain, or a codedomain.
 12. The UE of claim 8, wherein the processor is furtherconfigured to, based on detecting the WUS, control the RF transceiver toreceive the paging signal in a paging occasion related to the WUS. 13.The UE of claim 8, wherein the index information indicating the WUSgroup for the UE hops over time.
 14. The UE of claim 13, wherein ahopping pattern for the index information indicating the WUS group forthe UE is determined based on a system frame number (SFN).
 15. Anapparatus for a user equipment (UE) in a wireless communication systemsupporting NarrowBand Internet of Things (NB-IoT), the apparatuscomprising: a memory including executable codes; and a processoroperatively coupled to the memory, wherein the processor is configuredto perform specific operations by executing the executable codes, thespecific operations comprising: determining index information indicatinga wake-up signal (WUS) group for the UE, wherein a WUS resource for theUE is selected based on the determined index information; and monitoringa WUS for the UE based on the selected WUS resource, wherein the indexinformation indicating the WUS group for the UE is determined based onidentification information of the UE, parameters related to adiscontinuous reception (DRX) cycle of the UE, a sum of weights forpaging carriers, and information about a number of UE groups for theWUS.